Clutch system

ABSTRACT

The invention relates to a clutch system, comprising at least one clutch device, especially for arrangement in a drive train, between a drive unit and a transmission. Said clutch device ( 202 ) can be actuated through the conveying of a pressure medium and/or is able to operate under the influence of an operating medium. One aspect of the invention provides that a secondary medium that acts as the pressure medium for actuating or as the operating medium for operating the clutch arrangement is supplied by a pump arrangement ( 208 ) which supplies a primary medium and a secondary medium supply device ( 220 ) which is connected to the pump arrangement or a secondary pump arrangement ( 220 ). Said secondary medium supply arrangement or secondary pump arrangement has the following: at least one pressure absorption element which is movably arranged in a housing, which during operation, is exposed to the primary medium that is supplied by the first-mentioned pump arrangement, on at least one pressure absorption surface, and which can be caused to move by conveying the operating medium; and at least one interactional element which is movably arranged in the/a housing, which is motionally coupled to the pressure absorption element, which during operation, interacts with the secondary medium on at least one interactional surface, and whose action enables the supply of the secondary medium, optionally by displacement and/or introducing an acceleration and/or introducing a swirl.

TECHNICAL FIELD

[0001] The invention is directed to a clutch system comprising at least one clutch device, particularly for arrangement in a drivetrain (especially in a motor vehicle) between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which is provided for operation under the effect of an operating medium and/or which can be actuated through the intermediary of pressure medium.

PRIOR ART

[0002] Reference is made herein in particular, but not exclusively, to a wet multi-disk clutch arrangement. Further, reference is made herein above all, but not exclusively, to a clutch arrangement which can be actuated by hydraulic means with a hydraulic slave cylinder integrated in the clutch device as is disclosed, for example, in EP 0 758 424 B1 or in one of the present Applicant's patent applications concerning multiple clutch devices (particularly dual clutch devices). Reference is had particularly to the German patent applications 199 55 365.3 (AT 17.11.1999); 100 04 179.5, 100 04 186.8, 100 04 184.1, 100 04 189.2, 100 04 190.6, 100 04 195.7 (all AT 01.02.2000); 100 34 730.4 (AT 17.07.2000) of the Applicant, the disclosure of which is incorporated by reference in the disclosure of the present application. The clutch arrangements of the referenced clutch devices are wet multi-disk clutch arrangements. Further, DE 198 00 491 A1 can be referred to with respect to wet, hydraulically actuated multi-disk clutch arrangements. A dry hydraulically actuated dual clutch device is known from DE 35 26 630 A1.

[0003] In principle, there are many possible ways in which operating medium, possibly a cooling liquid (especially cooling oil), is supplied to the clutch arrangement or to a plurality of clutch arrangements of the clutch device. It is the job of the designer to keep the costs and space requirement as low as possible on the one hand and on the other hand to provide for a good efficiency and, accordingly, a low energy consumption for supplying the operating medium. In some cases, other marginal conditions must be accounted for as well. In case of a clutch device with one or more wet, hydraulically actuated clutch arrangements (particularly multi-disk clutch arrangements), a flow of hydraulic medium must be supplied for controlling the clutch device or clutch devices in order to engage (normally open type clutch) or disengage (normally closed type clutch) the clutch device or clutch devices. A relatively small volume flow at relatively high pressure is needed for engaging and disengaging. Further, a large volume flow of coolant, particularly cooling liquid (generally oil), is required for wet operation or for cooling of the clutch devices, wherein a volume flow at a lower pressure level is sufficient or even necessary.

[0004] It would be conceivable to provide two separate pumps which are driven by motor (e.g., determined by the drive unit and/or transmission) or by electric motor, one of which is designed to supply the pressure medium flow for controlling the clutch device or clutch devices and the other is designed for supplying the flow of operating medium. This solution is comparatively costly.

[0005] According to another approach described in DE 198 00 490 A1, a suction jet pump is provided in the supply area of a hydraulic fluid serving to cool a multi-disk clutch arrangement in order to achieve high throughflow rates and, therefore, a high cooling output. The suction jet pump receives a flow of hydraulic fluid from a hydraulic pump which provides a hydraulic pressure sufficient for actuating the multi-disk clutch arrangement. The suction jet pump sucks additional hydraulic fluid out of the oil pan.

[0006] While the hydraulic pump need not be designed for very high pumping outputs and a separate motor-driven pump for pumping coolant can be dispensed with using this approach of the prior art, the known approach based on the suction jet pump is disadvantageous insofar as the efficiency of the suction jet pump is comparatively poor due to the high vortex losses of a suction jet pump and the energy consumption is consequently relatively high.

DESCRIPTION OF THE INVENTION

[0007] Against this background, according to a first aspect, a clutch system is proposed according to the invention, which clutch system comprises at least one clutch device, particularly for arrangement in a drivetrain between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which is provided for operation under the action of an operating medium, operating medium can be supplied to the clutch arrangement for this operation by means of a pump arrangement supplying pressure medium and an operating medium supply arrangement which is connected to the pump arrangement and which provides the operating medium in a flow of operating medium with reduced pressure relative to a pressure medium whose pressure is given by the pump arrangement and, in relation to the medium volume supplied per time unit averaged over time, the operating medium flow is greater than a pressure medium flow possibly flowing from the pump arrangement to the operating medium supply arrangement, wherein the operating medium supply arrangement has at least one pressure receiving element which is arranged so as to be movable in a housing and which is exposed at least on at least one pressure receiving surface to the pressure medium which is provided by the pump arrangement in operation and can be set in motion through the intermediary of the pressure medium, and at least one interaction element which is arranged so as to be movable in the housing or a housing and which is coupled with respect to movement with the pressure receiving element and interacts during operation with the operating medium at least on at least one interaction surface, and the operating medium flow can be supplied through the intermediary of this interaction element.

[0008] Due to the operating medium supply arrangement according to the invention, operating medium can be provided economically and in a reliably operating manner with high efficiency and in a comparatively large volume flow. The operating medium supply arrangement can advisably be connected to an operating medium reservoir and can draw operating medium from the latter to supply to the clutch arrangement.

[0009] The operating medium supply arrangement can advisably be constructed as a pressure converter arrangement. According to an advantageous construction, the operating medium supply arrangement is constructed in such a way that the effective area of the pressure receiving surface exposed to the pressure medium is smaller per time unit averaged over time than the effective area of the interaction surface interacting with the operating medium.

[0010] An economical design is characterized in that at least one component is provided which is constructed integrally or in one piece and which forms the pressure receiving element or a pressure receiving element and the interaction element or an interaction element. For example, the component can advantageously be constructed as a piston arranged in a piston housing so as to be displaceable along an axis with a first piston surface exposed to the pressure medium and a second piston surface interacting with the operating medium. The first piston surface serves as a pressure receiving surface and the second piston surface serves as an interaction surface. The piston surfaces can be arranged at opposite axial end faces of the piston. The first piston surface is preferably smaller than the second piston surface.

[0011] Another embodiment form which is particularly advantageous with respect to the attainable volume flow is characterized in that at least one rotor component forms the pressure receiving element and/or the interaction element.

[0012] The particular construction of the operating medium supply arrangement notwithstanding, this can comprise a pump arrangement or can be identifiable as a pump arrangement.

[0013] In general, the clutch device can be actuated through the intermediary of the pressure medium supplied by the pump arrangement.

[0014] According to a second aspect, the invention provides a clutch system comprising at least one clutch device particularly for arrangement in a drivetrain (particularly in a motor vehicle) between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which can be actuated through the intermediary of pressure medium, wherein the pressure medium can be supplied for the actuation based on a pump arrangement supplying an operating medium and based on a pressure medium supply arrangement which is connected to the pump arrangement and which supplies the pressure medium at a pressure that is increased relative to a pressure of the operating medium that is given by the pump arrangement, and possibly in a flow of pressure medium which, with respect to medium volume supplied per time unit averaged over time, is smaller than an operating medium flow possibly flowing from the pump arrangement to the pressure medium supply arrangement, wherein the pressure medium supply arrangement has at least one pressure receiving element which is arranged so as to be movable in a housing and which is exposed in operation at least on at least one pressure receiving surface to operating medium supplied by the pump arrangement and can be set in motion through the intermediary of the operating medium, and at least one interaction element which is arranged so as to be movable in the housing/a housing and which is coupled with respect to movement with the pressure receiving element and interacts during operation with the pressure medium at least on at least one interaction surface, and the pressure medium can be supplied through the intermediary of the interaction element.

[0015] Due to the pressure medium supply arrangement according to the invention, operating medium can be provided economically and in a reliably operating manner with high efficiency and with a pressure level that is sufficient for clutch actuation. In this connection, the pressure medium supply arrangement can advisably be connected to a medium reservoir and can draw medium from the latter to supply the clutch arrangement and/or can conduct medium away to the medium reservoir. The pressure medium supply arrangement can also be constructed in such a way that it supplies operating medium drawn from the pump arrangement as pressure medium.

[0016] The pressure medium supply arrangement can advisably be constructed as a pressure converter arrangement. According to an advantageous construction, the pressure medium supply arrangement is constructed in such a way that the effective area of the pressure receiving surface exposed to the operating medium is larger per time unit averaged over time than the effective area of the interaction surface interacting with the pressure medium.

[0017] An economical design is characterized in that at least one component is provided which is constructed integrally or in one piece and which forms the/a pressure receiving element and the/an interaction element. For example, the component can advantageously be constructed as a piston arranged in a piston housing so as to be displaceable along an axis with a first piston surface which serves as a pressure receiving element and which is exposed to the operating medium and a second piston surface interacting with the pressure medium which serves as interaction surface. The piston surfaces can be arranged at opposite axial end areas of the piston. The first piston surface is preferably larger than the second piston surface.

[0018] Another advantageous embodiment form is characterized in that at least one rotor component forms the pressure receiving element and/or the interaction element.

[0019] Irrespective of the specific construction of the pressure medium supply arrangement, this can comprise a pump arrangement or can be identified as a pump arrangement.

[0020] Above all, the clutch device is intended for operation under the influence of an operating medium which can be supplied to the clutch device by the pump arrangement for this operation.

[0021] With respect to the clutch system according to the first aspect and with respect to the clutch system according to the second aspect, it is provided that a hydraulic medium is used as operating medium and as pressure medium.

[0022] According to a third aspect of the invention, a clutch system comprises at least one clutch device particularly for arrangement in a drivetrain (particularly in a motor vehicle) between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which is provided for operation under the influence of an operating medium and to which operating medium can be supplied for this operation based on a first pump arrangement (also referred to hereinafter as primary pump arrangement) which supplies pressure medium and a second pump arrangement (also referred to hereinafter as secondary pump arrangement) which is connected to the first pump arrangement and which can be driven by the pressure medium supplied by the first pump arrangement, wherein the secondary pump arrangement has at least one pump element which is arranged so as to be movable in a housing, can be driven through the intermediary of the pressure medium (also referred to hereinafter as primary medium), interacts with the operating medium (also referred to hereinafter as secondary medium), and conveys the secondary medium (operating medium) during operation by means of displacement and/or by imparting an acceleration and/or by imparting torsion or angular momentum in the direction of the clutch arrangement. The secondary pump arrangement which is provided according to the invention can be identified as an operating medium supply arrangement according to the first aspect of the invention.

[0023] Further, according to a fourth aspect, the invention provides a clutch system comprising at least one clutch device particularly for arrangement in a drivetrain (particularly in a motor vehicle) between a drive unit and a transmission, wherein the clutch device has at least one clutch arrangement which can be actuated through the intermediary of pressure medium, wherein the pressure medium can be supplied for this actuation based on a second pump arrangement (also referred to hereinafter as primary pump arrangement) supplying operating medium and a first pump arrangement (also referred to hereinafter as secondary pump arrangement) which is connected to the second pump arrangement and can be driven by the operating medium supplied by the second pump arrangement, wherein the secondary pump arrangement has at least one pump element which is arranged so as to be movable in a housing, can be driven through the intermediary of the operating medium (also referred to hereinafter as primary medium), interacts with the pressure medium (also referred to hereinafter as secondary medium) and, during operation, brings the secondary medium (pressure medium) to a pressure sufficient for clutch actuation by means of displacement and/or imparting an acceleration and/or imparting a torsion or angular momentum. The secondary pump arrangement which is provided according to the invention can be identified as a pressure medium supply arrangement according to the second aspect of the invention.

[0024] As a rule, in any case when the operating medium is a liquid, the second pump arrangement is connected to an operating medium reservoir and can draw operating medium from the latter for supplying to the clutch arrangement. The second pump arrangement can supply the operating medium in a operating medium flow which has a lower pressure than a pressure of the pressure medium that is given by the first pump arrangement and which, with respect to the medium volume supplied per time unit averaged over time, is greater than pressure medium flow possibly flowing from the first pump arrangement to the second pump arrangement or which can be supplied in its entirety in continuous operation by the pump arrangement.

[0025] With respect to the drive of the primary pump arrangement, it is intended above all that this primary pump arrangement can be driven electrically and/or through the intermediary of the drive unit and/or the transmission.

[0026] At least one of the first and second pump arrangements can comprise at least one hydrostatic pump or a pump constructed as a positive-displacement machine. Above all, it is intended that the first pump arrangement has at least one hydrostatic pump or pump constructed as a positive-displacement pump. Pumps of this kind are particularly suitable for building up high pressures and therefore—to mention one example—can advantageously supply the pressure that may be required for actuating the clutch arrangement. Examples for suitable pumps of the above-mentioned type, depending on requirements, are piston pumps, particularly axial piston pumps and radial piston pumps, toothed gear pumps and toothed ring pumps, vane cell pumps, screw pumps and rotary plunger pumps. Further or alternatively, at least one of the first and second pump arrangements can comprise at least one hydrodynamic pump or a pump constructed as a liquid flow machine. It is intended particularly that the second pump arrangement has at least one hydrodynamic pump, or pump constructed as a flow machine, that can be driven by pressure medium supplied by the first pump arrangement. Pumps of this kind are particularly suited to supply large volume flows, so that, if necessary, a large volume flow of operating medium can easily be supplied for feeding to the at least one clutch arrangement. Examples of pumps of this type are torque or swirl pumps and centrifugal pumps or impeller pumps.

[0027] For the application mentioned above with at least one hydraulically actuated wet multi-disk clutch arrangement, because of the comparatively high pressure at a comparatively small volume flow that is required for clutch actuation on the one hand and by reason of the comparatively high volume flow at a comparatively low pressure required for wet operation on the other hand, it seems advantageous when the first pump arrangement comprises at least one hydrostatic pump or pump constructed as a positive-displacement machine and when the second pump arrangement comprises at least one hydrodynamic pump or pump constructed as a flow machine. However, this design of the clutch system which is viewed as especially advantageous is in no way compulsory.

[0028] The pump (of the first or second pump arrangement) can have at least one pump element that can be driven in a translational or rotational manner and which can be driven by a motor, particularly an electric motor, in the case of a pump associated with the primary pump arrangement or which can be driven through the intermediary of the primary medium in case of a pump associated with the secondary pump arrangement. For example, the secondary pump arrangement can have at least one piston pump that can be driven by the primary medium supplied by the primary pump arrangement. The piston pump can have at least one piston which is arranged in a pump housing so as to be displaceable along an axis and with a first piston surface exposed to the primary medium and a second piston surface interacting with the secondary medium. The piston surfaces can be arranged at opposite axial end areas of the piston. In order to make use of or achieve the possibly high pressure level of the pressure medium on the one hand and/or to achieve or make use of a high operating medium delivery volume on the other hand, it can be advantageous when the piston surface associated with the pressure medium is smaller than the piston surface associated with the operating medium.

[0029] When only one piston is provided, the pump delivers the secondary medium in pulses because of an oscillating piston operation, so that the pump can also be referred to as an impulse pump. In order to provide an at least approximately continuous secondary medium flow and/or to prevent mechanical vibrations deriving from the oscillating movement of the piston, the secondary pump arrangement can have a plurality of piston pumps which can be operated synchronously with offset piston stroke phases. For example, a first piston pump and a second piston pump can be operated synchronously with piston stroke phases that are offset by approximately 180°. As a result of this kind of oppositely running operation of the two piston pumps, mechanical vibrations are sufficiently compensated or prevented.

[0030] The expenditure on control of the secondary pump arrangement is particularly low when an intake or suction stroke and a discharge stroke of the piston pump can be triggered alternately by means of a valve arrangement which is connected between the primary pump arrangement and the piston pump of the secondary pump arrangement. Either the suction stroke or the discharge stroke or both can be triggered by applying primary medium pressure to a control input of the piston pump associated with the respective stroke. The piston pump can have a return spring arrangement which is put under increasing tension during a suction stroke and discharge stroke.

[0031] It is suggested that at least one pressure reduction valve is provided, by means of which a primary medium pressure applied to a control input of the piston pump can be reduced by allowing the primary medium to flow off in order to trigger the suction stroke or discharge stroke of the piston pump.

[0032] The other respective stroke, the suction stroke or discharge stroke, can then be carried out by means of the return spring acting on the piston. When the valve arrangement is arranged between the primary pump arrangement and the piston pump it can form the pressure reduction valve or has this pressure reduction valve. However, the pressure reduction valve can also be a valve that is separate from said valve arrangement.

[0033] It is particularly preferable that the pressure reduction valve is integrated in the secondary pump arrangement. This avoids the flow resistance of longer lines so that the primary medium pressure can be reduced especially quickly, and a particularly high pump output can be achieved for the piston pump. The pressure reduction valve can be mechanically actuated through the intermediary of a stroke movement of a/the piston of the piston pump and/or through the intermediary of primary medium acting on the pressure reduction valve. In this connection, it is suggested by way of a further development that a plurality of valve elements of the pressure reduction valve are displaceable between a first relative position identified as opening position and a second relative position identified as the closing position in response to the stroke movement of the piston and/or in response to primary medium acting on at least one of the valve elements. For example, a first valve element and a second valve element can be provided which are pretensioned in the direction of the open position by a pretensioning spring arrangement. The piston can advantageously form a valve element.

[0034] In a particularly preferred manner, the pressure reduction valve can be moved into an/the open position in that a valve element executing the stroke movement along with the piston contacts a stop and/or in that the pressure reduction valve is actuated by the piston contacting an actuating stop and can be brought into a/the closing position by primary medium acting on at least one valve element. In this way, a compulsory control of the pressure reduction valve can be achieved to a certain extent, so that it need not be controlled separately.

[0035] In general, it is advantageous for a highly efficient secondary pump arrangement when the latter is constructed with at least one valve, particularly a non-return valve, which prevents secondary medium from the secondary pump arrangement (possibly from the piston pump) from flowing back into the secondary medium reservoir and/or with at least one valve, particularly a non-return valve, which prevents secondary medium from the side of the clutch arrangement from flowing back into the secondary pump arrangement (possibly into the piston pump).

[0036] According to an advantageous constructional variant, the secondary pump arrangement has at least one swirl pump or centrifugal pump (impeller pump) which can be driven by the primary medium supplied by the primary pump arrangement or at least one rotary positive-displacement pump, possibly a toothed gear pump or toothed ring pump, which can be driven by the primary medium supplied by the primary pump arrangement. As was already mentioned above, swirl pumps or centrifugal pumps can advantageously supply large volume flows, while positive-displacement pumps are particularly well suited for supplying higher pressures. The swirl pump or centrifugal pump or positive-displacement pump can have at least one rotor which interacts with the secondary medium. The rotor can be constructed as at least one blade or at least one rotor having another flow geometry or conveying geometry.

[0037] For purposes of driving the rotor, it is suggested that the latter can be driven by means of a hydromotor receiving primary medium from the primary pump arrangement. The hydromotor can be constructed as a flow machine (possibly a turbine) or positive-displacement machine. For example, a toothed gear motor or toothed ring motor, piston motor (particularly radial piston motor or axial piston motor) and a vane cell motor can be used. Generally speaking, the hydromotor can be constructed as a hydrostatic or hydrodynamic motor.

[0038] The hydromotor can be constructed as a rotary positive-displacement motor, for example, possibly as a toothed gear motor or toothed ring motor.

[0039] With regard to the prefix “hydro” (see hydromotor, hydrostatic pump, and hydrodynamic pump mentioned above) employed herein, this prefix does not exclude the possibility of a gaseous pressure medium and/or operating medium. Thus, in general, “pressure medium” designates a fluid under pressure and “operating medium” designates an operating fluid. Accordingly, the prefix “hydro” may also denote fluids. Therefore, instead of a “hydromotor” and a “hydrodynamic pump”, it would also be possible to speak of a “fluid motor” and a “fluid-dynamic pump”. Generally, however, the pressure medium and operating medium are liquid and can then also be designated as “pressure liquid” and “operating liquid.”

[0040] The rotor interacting with the secondary medium and/or the rotor of the hydromotor can comprise a disk and/or a shaft with a flow geometry arrangement, possibly a blade arrangement. Diverse designs of the swirl pump or centrifugal pump are possible. For example, the swirl pump or centrifugal pump can be constructed in such a way that the pumped secondary medium flows against the rotor in a substantially axial or radial-tangential direction and flows off the rotor in a substantially axial or radial-tangential direction. This applies in a corresponding manner to the hydromotor. The latter can be constructed in such a way that the primary medium flows against the rotor in a substantially axial or radial-tangential direction and flows off the rotor in a substantially axial or radial-tangential direction.

[0041] It is advantageous for the actual pump as well as for the hydromotor when a plurality of flow-in channels or flow-off channels which are arranged in a substantially rotational-symmetric manner with respect to the rotor are provided in a housing accommodating the rotor for essentially radial-tangential flow against the rotor in question and/or for essentially radial-tangential flow away from the respective rotor. Bearings associated with the rotor then need only absorb comparatively small radial forces and a comparatively low-friction running of the rotor is ensured.

[0042] An advantageous construction is characterized in that at least one rotor interacting with the primary medium and at least one rotor interacting with the secondary medium have rotational axes which are essentially coaxial with respect to one another. In this respect, it is suggested by way of further development that at least one operating medium flow is guided substantially in axial direction at least in some areas as an annular flow surrounding at least a pressure medium flow and/or surrounding the rotor interacting with the pressure medium flow. The pressure medium flow and the operating medium flow can pass into a common medium flow which is fed to the clutch device as an operating medium flow, for example. The combination of a pressure medium flow and the operating medium flow and the supply of the combined medium flow to the clutch device, particularly to the clutch arrangement, can also be provided in the other designs described above, and indeed for all of the aspects of the invention discussed. In this way, it can be achieved, for example, that a certain minimum supply of operating medium (operating liquid, particularly cooling oil) to the clutch device is ensured in case of a viscous operating medium at lower temperatures.

[0043] An advantageous embodiment form is characterized in that the secondary pump arrangement has at least two rotors which interact with the secondary medium and which are not arranged coaxial to one another and/or in that the hydromotor has at least two rotors which interact with the primary medium and which are not arranged coaxial to one another. This type of construction is particularly advisable for a secondary pump arrangement operating according to the principle of positive displacement or a hydromotor operating according to the principle of positive displacement.

[0044] With respect to the hydromotor, it is suggested by way of a further development that a drive formation, possibly a toothing, of a first rotor of the hydromotor meshes with a driving formation, possibly a toothing, of a second rotor of the hydromotor. With respect to the secondary pump arrangement, it is suggested by way of a further development that a conveying formation, possibly a toothing, of a first rotor of the secondary pump arrangement meshes with a conveying formation, possibly a toothing, of a second rotor of the secondary pump arrangement.

[0045] It will often be advisable that at least one rotor of the hydromotor interacting with the primary medium and at least one rotor of the secondary pump arrangement interacting with the secondary medium are coupled with one another by means of at least one common shaft which is shared by at least one rotor of the hydromotor and at least one rotor of the secondary pump arrangement. However, this is in no way mandatory. It can also be provided that a rotor of the hydromotor and a rotor of the secondary pump arrangement are arranged on a common shaft, while another rotor of the hydromotor and another rotor of the secondary pump arrangement are arranged on their own respective shafts which need not necessarily be rotationally coupled with one another as long as there is a coupling by means of the first rotor.

[0046] The clutch device (and the clutch arrangement) can be self-priming with respect to the operating medium. In this case, it is advantageous when the second pump arrangement allows operating medium which is sucked in by the clutch device (or clutch arrangement) to pass to the latter in a non-operational state. This makes possible an emergency operation, for example, when the second pump arrangement is defective. Also, it could be conceivable under certain circumstances to put the second pump arrangement out of operation, that is, to put it into the non-operational state, for certain operating states of the clutch system or drivetrain in order to save energy.

[0047] It has already been mentioned several times that the clutch arrangement can be actuated through the intermediary of pressure medium. It has already been made clear that it is intended in particular that the clutch arrangement can be actuated by means of pressure medium supplied by the pump arrangement according to the first aspect of the invention or by the first pump arrangement according to the third aspect of the invention. For this purpose, the pump arrangement or the first pump arrangement is designed to supply pressure medium at a pressure sufficient for actuating the clutch arrangement.

[0048] It is noted for the sake of clarity that the clutch device according to the second and fourth aspects of the invention can also be a clutch device which is provided for an operation under the influence of the operating medium supplied by the pump arrangement or by the second pump arrangement.

[0049] It has already been made clear that the clutch arrangement is intended above all to be a wet clutch arrangement, that the operation is a wet operation under the influence of the operating medium, and that the operating medium is an operating liquid, possibly a cooling liquid. Of the possible wet clutch arrangements, a multi-disk clutch arrangement is intended above all.

[0050] The pressure medium can be a hydraulic pressure medium, particularly a hydraulic oil which may also serve as a cooling liquid.

[0051] The clutch device can be a multiple clutch device with a plurality of clutch arrangements, for example, a dual clutch device with two clutch arrangements assigned to a transmission input shaft. In this connection, reference is had particularly to the design disclosed in the present Applicant's patent applications cited above.

[0052] It can be advisable to construct the clutch system in such a way that operating medium can be supplied to the clutch arrangement through the intermediary of an operating medium storage which is connected or can be connected to the operating medium supply arrangement or to the pump arrangement or to the second pump arrangement. Further, an advantageous construction can consist in that the clutch arrangement can be actuated through the intermediary of a pressure medium storage which is connected or can be connected to the pump arrangement or to the pressure medium supply arrangement or to the first pump arrangement.

[0053] The invention will be described in the following with reference to a number of embodiment examples shown in the drawings which are not to be considered as limiting the field of the invention. The examples according to FIGS. 11 and 12 primarily illustrate the above-discussed approach using two separate pumps, in contrast to the aspects of the invention treated above. However, these examples can also help to clarify the aspects of the invention and show possible constructions of a clutch system according to the invention.

[0054]FIG. 1 is a schematic view of an embodiment example of a clutch system having a wet dual clutch;

[0055]FIG. 2 is a sectional view of a piston device which is usable as a pressure converter or pump and can be used as a component P of the arrangement according to FIG. 1;

[0056]FIG. 3 is a view in partial section of a rotor device which can be used as a pressure converter or pump and can be used as a component P of the arrangement according to FIG. 1;

[0057]FIG. 4 is an axial view in partial section viewed in direction IV in FIG. 3 of a rotor of the rotor device which is driven by pressure fluid, including a pressure fluid supply channel and a pressure fluid discharge channel;

[0058]FIG. 5 is a view corresponding to FIG. 4 showing a variant of the rotor driven by pressure fluid with two pressure fluid supply channels and two pressure fluid discharge channels arranged symmetrically with respect to the axis of rotation of the rotor;

[0059]FIG. 6 is a sectional view along section line VI-VI in FIG. 3 showing a rotor of the rotor device which conveys operating medium and which is driven by the pressure medium through the intermediary of the rotor of FIG. 4 or 5 and a rotational coupling of the two rotors;

[0060]FIG. 7 shows a view in partial section of the rotor of FIG. 6 viewed in direction VII in FIG. 3;

[0061]FIG. 8 shows another embodiment example of a rotor device which can serve as pump or pressure converter and which is usable as component P in the arrangement according to FIG. 1;

[0062]FIG. 9 is a schematic view showing another embodiment example of a clutch system which has a wet dual clutch;

[0063]FIG. 10 is a sectional view of a piston device which is usable as a pressure converter or pump and which can be used as component P of the arrangement according to FIG. 9;

[0064]FIG. 11 is a schematic view of an embodiment example of a clutch system with two pumps which are associated with a wet dual clutch and are driven by electric motor;

[0065]FIG. 12 shows an example of how a clutch system of the type corresponding to FIG. 11 could actually be constructed;

[0066]FIG. 13 is a view in partial section showing a dual clutch with two multi-disk clutch arrangements which is arranged in a drivetrain of a motor vehicle between a transmission and a drive unit and which could be the component part of a clutch system according to the invention;

[0067]FIG. 14 is a view in partial section showing another example of a rotor device which can be used as a pressure converter or pump and which can be used as component P of the arrangement according to FIG. 1 or as component P of the arrangement according to FIG. 9;

[0068]FIG. 15 shows the rotor device from FIG. 14 in a partial sectional view along section line XV-XV;

[0069]FIG. 16 shows the rotor device from FIG. 14 in a sectional view along section line XVI-XVI;

[0070]FIG. 17 shows a divided sealing disk of the rotor device in an axial top view;

[0071]FIG. 18 shows a constructional variant of the rotor device of FIG. 14 in a schematic partial sectional view.

[0072]FIG. 1 is a schematic view showing a clutch system 200 which has a wet dual clutch 202 with a first, radially inner clutch device 204 and a second, radially outer clutch device 206. The clutch devices 204 and 206 are wet clutch devices, for example, wet multi-disk clutch devices which have, in a manner known per se, at least one disk stack, are arranged one upon the other radially in the present embodiment example, and are actuated in each instance by an associated actuating piston of a hydraulic slave cylinder integrated in the dual clutch. Examples of dual clutches of this type are disclosed in EP 0 758 434 B1 and in the German patent applications cited in the preceding.

[0073] A basic problem in clutches of this kind is that a high pressure is generally required at a small volume flow for actuating the clutch devices, especially the disk stacks, whereas a low pressure at a high volume flow is required for wet operation of the clutch devices, particularly for cooling the disk stacks. In order to be able to meet both of these conflicting requirements, two different, mutually independent pumps can be provided. However, due to the high space requirement this creates problems with respect to design and also economically because of the comparatively high cost, depending on the type and drive of the pumps.

[0074] In contrast, a pump 208 is provided in the arrangement according to FIG. 1 which is driven by an electric motor 210 and sucks hydraulic medium (particularly hydraulic oil) from a hydraulic reservoir 212, this hydraulic medium being conveyed further to valves 214, 216 and 218. The pump 208 generates a sufficiently high pressure to dependably to actuate the clutch devices 204, 206, so that the associated clutch device is actuated—engaged in case of a “normally open” clutch according to the valve state of the valve in question or disengaged in case of a “normally closed” clutch according to the valve state of the respective valve—as soon as one of the valves 214 and 216 is switched to open.

[0075] The valve 218, together with component P which is designated by reference number 220, serves to convert the pressure at the input side of valve 218 at a small volume flow into a low pressure with a large volume flow. Accordingly, the subassembly formed by the valve 218 and component P (220) has pressure-converting characteristics. In order to supply a larger volume flow of operating medium, in this case cooling oil, component P is connected to an oil reservoir 222. It is not compulsory that the reservoir 222 is a separate reservoir from reservoir 212. The component P provides at least one operating medium flow, in this case a flow of cooling oil, which is conducted to the clutch devices 204, 206, particularly to their disk stacks in case of the present example.

[0076] Therefore, component P or the subassembly formed by component P and valve 218 is considered as a pump arrangement. Embodiment examples of devices that can be used as component P are mentioned in the following. To the extent that these devices are designated as “pump” or “pump arrangement” in the following, this in no way confines or limits the subject matter of the invention. However, there is no question but that the component P can be realized on the basis of at least one pump or one pump arrangement corresponding to an aspect of the invention. A further aspect of the invention is directed to the pressure conversion of the comparatively high clutch actuation pressure supplied by the pump 208 into a lower pressure with a greater volume flow for the clutch cooling, which pressure conversion is achieved according to the arrangement in FIG. 1.

[0077]FIG. 2 shows a piston device 230 which can be used as component P and which has a piston 234 which is mounted in a housing 232 so as to be displaceable along an axis A. The piston device 230 has a connection 236 at which the piston device serving as component P is connected to the valve 218. The piston device is connected to the reservoir 222 via another connection 238. The dual clutch 202 is supplied with the cooling oil via a third connection 240.

[0078]FIG. 2 shows the piston 234 and a valve element 242 cooperating with the latter in two different positions, one of which is shown in the half-plane above the axis A and the other in the half-plane below the axis A. The position of the piston and of the valve element shown in the upper half-plane is occupied by the piston 234 and the valve element 242 at the end of a stroke of the piston 234 which is carried out under the action of a return spring 244 and which can be identified as the “suction stroke” and of a stroke of the valve element 242 which moves along with the piston 234. A pressure reduction valve 246 which is formed by the piston 234 and the valve element 242 is closed and an interior space 250 of the piston device is filled with cooling oil that is sucked in via the connection 138 and a non-return valve 252. The piston 234 and the valve element 242 are pretensioned or biased with respect to one another in the opening direction of the pressure reduction valve 246 by a valve spring 254. However, the piston 234 and the valve element 242 occupy the closed position since the valve element 242 is pushed by a valve shaft at a housing portion and the spring force of the return spring 244 is sufficient to displace the piston 234 against the action of the spring 254 into a stop position in which the piston 234 stops at the housing by a piston portion extending in radial direction and closes the pressure reduction valve 246 in cooperation with the valve element 242. The spring 244 which preferably acts directly at the above-mentioned piston portion is supported at a closure plate 258 which closes the interior space 250 and which is held at the housing 232 by a snap ring 256.

[0079] The piston position and valve position shown in the upper half-plane are occupied when a comparatively low pressure prevails in another interior space 260 of the piston device, so that the return spring 244 can move the piston 234 and the valve element 242 into the stop position shown in the drawing. The valve 218 is then closed. When pressure oil supplied via connection 236 by the pump 208 is conducted into the interior space 260 at comparatively high pressure by switching the valve 218 which, in the simplest case, is constructed as a lift valve, this pressure oil acts on a first piston surface 262 of the piston and an associated 264 of the valve element 242. Since forces exerted by the pressure oil in the interior space 260 on the pressure receiving surface 264 are conducted away via the valve spring 254 and a contact of the piston 234 and valve element 242 against one another in a positive-locking connection closing the pressure reduction valve 246, the actual piston surface or pressure receiving surface 262 of the piston on the one hand and the pressure receiving surface 264 of the valve element 242 on the other hand can be taken into account jointly in the form of an individual effective piston surface associated with the pressure oil.

[0080] The pressure oil in the interior space 260 displaces the piston 234 and the valve element 242 together in the direction of the closure plate 258 against the action of the return spring 244. In so doing, cooling oil is displaced from the interior space 250 via a non-return valve 266 and the connection 240 in the direction of the dual clutch 202. Accordingly, the piston 234 executes a “discharge stroke.” This discharge stroke ends when the piston 234 strikes against a stop ring 268 which is held inside the interior space 250 at the housing 232 in the manner of a snap ring. Shortly before the piston 234 stops against the stop ring 268, the valve shaft of the valve element 242 strikes a stop pin 270 which is arranged at the closure plate 258, so that the valve element 242 can not take part in the rest of the discharge stroke along with the piston 234. The pressure of the pressure oil in the interior space 260 is sufficient for the pressure oil acting on the first piston surface 262 to move the piston 234 into its stop position while releasing the valve element 242 until the piston 234 stops against the stop ring 268. The pressure reduction valve 246 which was previously held in its closed position by the pressure oil in the interior space 260 against the action of the valve spring 254 accordingly opens so that pressure oil can flow out of the interior space 260 through a passage formed between the piston 234 and the web of the valve element 242 into the interior space 250. This situation is shown in the lower half-plane of FIG. 2; a passage can be seen between an annular flange having the pressure receiving surface 264 and an associated end portion of the piston 234. The piston position and valve position shown in the lower half-plane or a somewhat different position corresponding to a pressure and force equilibrium to be adjusted is occupied until pressure oil is subsequently delivered into the interior space 260 via the valve 218 and the connection 236. When the valve 218 is closed, the returning movement of the piston 234 corresponding to the “suction stroke” and the returning movement of the valve element 242 into the position shown in the upper half-plane is initiated under the influence of the return spring 244. The pressure reduction valve 246 remains open under the action of the valve spring 254 until the valve shaft of the valve element 242 strikes against the housing. Cooling oil is again sucked out of the reservoir 222 during this “suction stroke.”

[0081] The piston device according to FIG. 2 has pressure-converting characteristics. On the side of the interior space 250, the piston has a second piston surface 280 which is appreciably larger than the first piston surface 262 or the effective piston surface formed by the first piston surface 262 and the pressure receiving surface 264. Due to the other effective piston surface on the side of the pressure oil drawn from the pump 208 and the larger piston surface on the side of the cooling oil drawn from the reservoir 222, a greater pressure in interior space 260 can balance out a small pressure in interior space 250, and the forces exerted on the piston 234 by the return spring 254 are also taken into account in addition. In practical operation of the piston device, an equilibrium state of this kind need not occur, the pressure in the interior space 250 can be substantially less than an equilibrium pressure corresponding to a pressure conversion according to the piston surfaces depending on the flow resistance through the non-return valve 266, the connection 240, an oil connection to the dual clutch 206 and an effective flow resistance of the dual clutch 202 and a return line into the reservoir 222 during the entire discharge stroke when the pressure reduction valve is closed.

[0082] The piston device makes it possible that through the intermediary of the small piston surface on the pressure oil side and by means of the high pressure of the pressure oil and through the intermediary of the large piston surface on the cooling oil side at low pressure, a volume quantity conveyed for cooling the clutch is greater than the amount of pressure oil supplied to the piston device via the valve 218. It should be mentioned that a pressure compensation opening 282 is provided in the housing 238 in FIG. 2, which pressure compensation opening 282 is connected to the reservoir 222 in order to prevent the piston 234 from sticking in its stop position shown in the upper half-plane due to a vacuum.

[0083] The non-return valve 252 serves to prevent cooling oil from flowing out of the interior space 250 back into the reservoir 222. Alternatively, this non-return valve could also be formed in the piston as is indicated in dashed lines at 252′. In this case, a connection of the piston device associated with the pressure compensation opening 282 will be sufficient and connection 238 could be dispensed with. The non-return valve 266 prevents cooling oil from the side of the dual clutch from flowing back into the interior space 250.

[0084] The piston device works to supply fresh oil continuously to the dual clutch with reciprocating pistons and consequently with a pulsed delivery of fresh oil to the dual clutch. Therefore, the piston device may also be called a pulse delivery pump. Vibrations can occur under certain circumstances due to the oscillating motion of the piston. In order to remedy this, two piston devices can be operated in parallel and in opposite directions, that is, with a phase of the piston stroke that is offset by 180°, approximately in the manner shown in FIG. 2. Of course, both piston devices can be constructed with an individual housing shared by both devices and with common connections. It is also possible for more than two piston devices to be connected in parallel and operated with mutually offset stroke phases for a more uniform supply of fresh oil.

[0085]FIG. 3 shows a rotor device 300 which can be used as component P (220) in the arrangement according to FIG. 1. The rotor device has at least one pressure medium connection 302 which is connected to the pump 208 either via the valve 218 or directly and a cooling connection, not shown in the drawing, which is connected to the reservoir 222 and from which cooling oil can flow via a non-return valve 304 in a housing 306 of the rotor device 300 which is constructed in multiple parts into a conveying rotor 308 having at least one conveying geometry, for example, a vane or blade shape.

[0086] Pressure oil flowing into the housing 306 via the connection 302 flows against at least one drive rotor 310 which is constructed with at least one pulse geometry or rotational pulse receiving geometry, for example, a vane shape, and is set in rotation by the pressure oil.

[0087]FIG. 4 shows a possible construction of the drive rotor 310 in detail. Several blade geometries 312 are shown. The pressure oil which is directed through a supply channel 314 to the blade geometries 312 sets the rotor 310 in rotation in the direction indicated by arrow 315. After interacting with the rotor, the pressure oil which has now given off a portion of its energy flows off via a flow-off channel 316.

[0088] The conveying rotor 308 is connected with the drive rotor 310 so as to be fixed with respect to rotation relative to it. FIG. 6 and FIG. 7 show an example for the construction of the conveying geometries which in this case are blade-shaped. They can also be called conveying blades 318. In the present embodiment example, the blade geometries 312 of the drive rotor and the conveying geometries 318 of the conveying rotor are arranged at a rotating disk 320 which is mounted radially and axially in the housing 306. The disk 320 on the one hand and the drive rotor 310 formed by the blade geometries 312 and a hub portion 322 and the conveying rotor 308 formed by the conveying geometries 318 on the other hand can be constructed in one part or multiple parts. For example, it could possibly be produced as a plastic part in one piece.

[0089] According to the preceding, the conveying rotor 308 is driven in rotation by the pressure oil flowing against the drive rotor 310 via the channel 314 through the intermediary of the drive rotor. The rotation of the conveying rotor 208 generates a cooling oil flow from the reservoir 222 via the associated connection of the rotor device, the non-return valve 304 to the conveying rotor 308 and the cooling oil interacting with the conveying rotor is guided via a flow-off channel 330 and a connection of the piston device associated with the dual clutch 202 to the dual clutch 302, or more exactly to its clutch devices 204 and 206. The conveying effect of the conveying rotor 308 relies on torsion imparted to the cooling oil and/or on the action of centrifugal force of the cooling oil accelerated through the intermediary of the conveying rotor, so that the rotor device 300 can also be designated as a swirl pump, in this case specifically as an impeller pump or centrifugal pump.

[0090] The flow-off channel 316 guiding the pressure oil opens at 332 into the supply channel 330, so that the pressure oil is conveyed together with the cooling oil to the dual clutch 202. In case of the embodiment example shown in the drawing, the pressure oil supplied by the pump 208 on the one hand and the cooling oil conveyed from the reservoir 222 to the dual clutch 202 on the other hand are the same medium, that is, a hydraulic oil.

[0091] The conveying geometries, in this case blade geometries 318, are shaped in such a way that large volume flows can be conveyed through the dual clutch 202 during a rotational movement of the conveying rotor 308 and cooling oil can flow from the reservoir 222 through the rotor device 300 to the dual clutch 202 when the conveying rotor 308 is stationary in the case of a self-priming clutch.

[0092] In the embodiment example shown in the drawing, pressure oil flows against the blade geometries 312 of the drive rotor 310 radially and tangentially and the pressure oil flows off from the blade geometries 312 tangentially or radially. The cooling oil that is sucked in flows against the blade geometries 318 of the conveying rotor 308 axially and the cooling oil flows off in radial direction. Other flow conditions are also possible. For example, flow can proceed against the driving rotor axially.

[0093] The comparatively costly sliding bearing or rolling bearing for the bearing support of the rotors can be dispensed with when a lubricating film bearing is provided. The rotor device can be constructed in such a way that a corresponding lubricating film is formed compulsorily based on the rotational movement, e.g., based on a hydrodynamic effect. However, supply openings can be provided through which small amounts of pressure oil and/or cooling oil are conducted to the lubrication points. An opening of this kind is shown at 334.

[0094] The rotating disk 320 serving to support the rotors can be provided at its circumference and/or at its axial end faces with a friction-reducing coating, e.g., PTFE, for a particularly low-friction bearing support. Accordingly, the transition from adhesive friction to sliding friction in particular is accelerated.

[0095] The following should lead to a better understanding of the drawings. The rotational movement imparted to the conveying rotor 308 is represented in FIGS. 6 and 7 by arrow 340. The circular line 342 represents the outer circumference of the rotating disk 320. The dashed circular lines 344 and 346 do not represent design details of the rotor device 300, but rather correspond to the rotational movement path of the radial outer blade ends of the drive rotor and conveying rotor. The circular line 348 represents the inner circumference 350 of a cooling oil channel 352 in the interior of the housing 306 which guides cooling oil from the non-return valve 304 to the conveying rotor 308. The radial position of this inner circumference is also shown in FIG. 7 by a dashed circular line 352. The arrows 354 show the flow direction of the pressure oil to the drive rotor 310 and away from the latter. The arrows 356 show the flow direction of the cooling oil to the conveying rotor 308 and away from the latter.

[0096] In order to ensure that the drive rotor 310 starts with the least friction possible, flow can proceed against the drive rotor 310 or its blade geometries 312 in a rotationally symmetric manner. According to a constructional variant shown in FIG. 5, two supply channels 314 which are offset by about 180° and two flow-off channels 316 which are offset relative to one another by 180° are formed in the housing 306. For example, three supply channels which are offset by 120°, four supply channels which are offset by 90° relative to one another, etc., could be provided.

[0097] The function of the non-return valve 304 is referred to in the following. The non-return valve 304 generally ensures that no oil flows out of the rotor device into the reservoir (compensation vessel) 222. In particular, pressure oil flowing via the connection 302 to the drive rotor 310 and from the latter via the flow-off channel 316 into the channel 360 is prevented from flowing off into the reservoir 222. The fact is that at low temperatures the cooling oil in the reservoir 222 can be quite viscous and therefore under some circumstances, e.g., after the motor vehicle has stood for a long time, can not be sucked in immediately in sufficient quantities. The pressure oil flowing into the channel 360 then ensures a minimum supply of cooling medium to the clutch device.

[0098] Another rotor device 400 which can be used as component P (220) in the arrangement according to FIG. 1 is shown in a perspective view in FIG. 8. The rotor device 400 has a rotating shaft 404 which is rotatably mounted in a housing 402. The rotating shaft 404 has at least one drive rotor 410 with pulse or rotary pulse receiving geometries, in this case especially blade geometries 412, and at least one conveying rotor 408 with conveying geometries, in this case especially blade geometries 418. The drive rotor 410 is associated with a high-pressure turbine drive and pressure oil flows against it axially as is indicated by the arrow 420. Referring to the arrangement according to FIG. 1, this pressure oil having a relatively high pressure is supplied by the pump 208 which is connected via the valve 218 or directly to a connection of the rotor device 400 associated with the drive rotor 410.

[0099] The housing 402 has a radial inner cylinder 421 and a radial outer cylinder 422. The inner cylinder 421 receives the drive rotor 410 and guides the pressure oil in an axial flow to the drive rotor 410. Between the outer cylinder 422 and the inner cylinder 421, a cooling oil pressure flow represented by arrow 424 is guided axially to the conveying rotor 408 which is arranged at the other side of an axial end of the inner cylinder 421 and whose blade geometries 418 extend farther radially outward than the outer circumference of the inner cylinder 421. The pressure oil which has passed the drive rotor 410 exits from the inner cylinder 421 and flows together with the cooling oil in the region of the conveying rotor 408.

[0100] In addition to the rotors 408 and 410, which are shown in FIG. 8 and which can also be referred to as impellers, conducting devices that are stationary with respect to the housing can be provided in order to make efficient use of the kinetic energy of the pressure oil for the driving of the drive rotor 310 and therefore (via shaft 404) for the driving of the conveying rotor 208 and in order to convey the cooling oil through the intermediary of the conveying rotor 408 in an efficient manner. In the present embodiment example, the conveying effect of the rotating conveying rotor is based on the fact that angular momentum or swirl is imparted to the pressure oil. Accordingly, one can say that the conveying rotor 408 forms a swirl conveying pump.

[0101] In a corresponding manner, as in the case of the rotor device 300, the radial bearing and axial bearing supporting the rotors, that is, the radial bearing and axial bearing supporting the shaft 404, can provide a lubricating film bearing which compulsorily forms during the rotational movement, particularly in a hydrodynamic manner. A compulsory lubrication can also be provided by supplying pressure oil and/or cooling oil. Also, for the embodiment form in FIG. 8, a coating, e.g., of the bearing portions of the rotating shaft 404, for example, a PTFE coating, is advantageous for reducing friction so that the mixed friction region can be traversed more quickly when accelerating.

[0102] When the conveying rotor is stopped, conveying oil which is sucked in through a self-priming dual clutch can flow through the blade geometries 418 of the conveying rotor 308 without excessive flow resistance.

[0103] There is an important difference between the embodiment form according to FIG. 2 and the embodiment forms according to FIGS. 3 to 8. With regard to the conveying of the cooling oil, the piston device 230 works as a hydrostatic pump or, viewed in another way, as a positive-displacement machine. In contrast, the rotor devices 300 and 400 which can be designated as swirl conveying pumps with respect to the conveying of cooling oil operate as hydrodynamic pumps or, viewed in another way, as liquid flow machines. Such hydrodynamic pumps or flow machines are particularly well suited for generating high volume flows, whereas hydrostatic pumps or positive-displacement machines, especially piston pumps or piston machines, are not necessarily the first choice for generating higher volume flows. Since, on the other hand, hydrostatic pumps or positive-displacement machines, particularly piston pumps, are generally more suitable for generating high pressures than are hydrodynamic pumps or flow machines, the pump 208 supplying the pressure oil is constructed as a hydrostatic pump or positive-displacement machine in a particularly preferred construction of the arrangement according to FIG. 1.

[0104] In the embodiment examples described above, a comparatively large flow of cooling medium, particularly cooling oil, which is at comparatively low pressure is generated through the intermediary of a pressure medium, particularly pressure oil, having a comparatively high pressure and through the intermediary of a comparatively small volume flow of this pressure medium. Conversely, a (possibly comparatively smaller) pressure medium flow, particularly a flow of pressure oil, can also be generated with comparatively high pressure through the intermediary of a cooling medium flow, particularly a flow of cooling oil at comparatively low pressure by using a corresponding pressure converter. FIG. 9 shows a corresponding embodiment example for a clutch system according to the invention. In this case, the pump 208 a which is driven by the electric motor 210 a is designed for supplying a large-volume flow of cooling oil for cooling the clutch arrangements 204 a and 206 a of the dual clutch 202 a, wherein the pump 208 a generates a cooling oil pressure that would not be sufficient in terms of pressure to actuate the clutch devices 204 a and 206 a. A pressure converter 220 a (component P) is connected to the cooling oil pump 208 a, possibly via a valve 218 a, and supplies pressure oil at a pressure level sufficient for actuating the clutch devices 204 a and 206 a under the influence of the cooling oil. For this purpose, the clutch devices are connected to component P via the valves 214 a and 216 a. Component P can be connected to the reservoir 112 a by means of a separate line in order to suck hydraulic oil out of the latter and/or to deliver hydraulic oil to the reservoir depending on the construction and function of component P. In principle, component P can be constructed as a positive-displacement machine or flow machine, possibly a hydrostatic pump or hydrodynamic pump, in a manner analogous to that discussed with reference to the piston device 230 and the rotor devices 300 and 400, wherein, however, a small input pressure is converted to a high output pressure. One possibility would be to construct component P as a piston device similar to piston device 230, wherein a large piston surface is associated with the cooling oil and a small piston surface is associated with the pressure oil to be put under pressure.

[0105] Since a comparatively large volume flow is required for cooling the dual clutch, the pump 208 a can advantageously be constructed as a hydrodynamic pump.

[0106]FIG. 10 shows a piston device 500 which can be used as component P in the arrangement according to FIG. 9 and which is connected, for example, to the valve 218 a of the arrangement according to FIG. 9. The reference numbers used to describe the piston device 230 shown in FIG. 2 will be used—with 300 added—in the following description of piston device 500. Therefore, the preceding description of the piston device 230 can easily be applied to the piston device 500 and only the differences between them will be discussed.

[0107] The piston device is connected via its connection 536 and valve 218 to the cooling oil pump 408 a. The valve 218 a accordingly lets cooling oil into the interior space 560 corresponding to the pressure generated by the pump 208 a for bringing about a “discharge stroke” against the action of the return spring 544 and lets off cooling oil contained in the interior space 560 in the reservoir 212 a to reduce the pressure in the interior space 560 in order to initiate or permit a “suction stroke” under the action of the return spring 544. During the suction stroke, hydraulic oil is sucked out of one of the reservoirs 112 a and 222 a, for example, into the interior space 550 via the connection 538 and the non-return valve 552. During the discharge stroke, corresponding to the axial displacement of the piston 534, hydraulic oil is supplied as pressure oil from the interior space 550 via the non-return valve 566 and the connection 540 to an actuating pressure oil circuit which can be constructed as a pressure oil reservoir in order to supply a uniform pressure level for the clutch actuation. A reservoir 221 a of this kind is shown in dashed lines in FIG. 9 as a possible construction of the clutch system. This reservoir can easily be associated with respect to construction and/or function with component P, e.g., integrated into component P.

[0108] Piston 534 has a first piston surface 562 which is exposed to the cooling oil in the interior space 560 and which is appreciably larger than the second piston surface which is arranged at the other end of the piston and which is exposed to the hydraulic oil that is contained in the interior space 550 and is to be supplied for clutch actuation. Therefore, also taking into account the axial forces exerted on the piston surface by the return spring 544, the comparatively lower pressure in the interior space 560 can be converted into a comparatively high pressure in interior space 550, so that the pressure oil flowing off via the connection 540 is at a pressure level which is sufficient for reliable actuation of one or both clutch arrangements 204 a and 206 b.

[0109]FIG. 11 illustrates an embodiment example of a clutch system which is based on another approach and which has two mutually independent pumps. A first pump 208 b and a second pump 209 b are provided and are driven by an electric motor 210 b and 211 b, respectively. The first pump 208 b which is driven by an electric motor and which is preferably constructed as a hydrostatic pump or positive-displacement machine supplies pressure medium, particularly pressure oil, at a comparatively high pressure which is sufficient to actuate the clutch devices 204 b and 206 b of the dual clutch 202 b. For selective actuation of the clutch devices, these clutch devices are connected to the pump 208 b via an associated valve 214 b or 216 b.

[0110] The second pump 209 b which is driven by an electric motor and which is preferably constructed as a hydrodynamic pump or flow machine supplies a comparatively large volume flow of cooling medium, particularly cooling oil, which is sufficient for cooling the clutch devices 204 b and 206 b. The pressure delivered by the pump 209 b can be appreciably less than the pressure delivered by the pump 208 b.

[0111]FIG. 12 shows another embodiment example with two pumps which are driven independently, preferably by electric motor. The reference numbers in FIG. 11 are also used in FIG. 12 insofar as the various components of the clutch system of FIG. 12 correspond to the components of the arrangement according to FIG. 11.

[0112] In accordance with the fundamental idea that the cooling of the dual clutch 202 b requires a high volume flow at comparatively low pressure, the electrically driven pump 209 b is preferably a hydrodynamic pump, for example, an impeller pump. Since the clutch arrangements must generally only be cooled very intensively when stopping or starting, it is sensible to construct and control this pump in such a way that the rotational speed is controlled or regulated corresponding to the cooling requirement as is indicated in FIG. 12 by a pump symbol with an arrow. Very high conveying flows can be achieved with a hydrodynamic pump, particularly an impeller pump. For example, in a conventional impeller pump the conveying flow increases in proportion to the square of the pumping speed.

[0113] According to FIG. 12, the cooling oil is supplied to the dual clutch 202 b via a heat exchanger 600, since a noticeable increase in temperature can come about also in the oil in the oil pan 212 b, for example, in case of a long slip operation. The oil temperature is maintained at a temperature level sufficient for cooling the dual clutch by means of the heat exchanger 600. Since the cooling oil can be quite viscous at lower temperatures and in certain cases cooling oil would no longer reach the dual clutch in sufficient quantities because of the flow resistance of the heat exchanger 600 at especially low temperatures, a bypass valve 602 which is pretensioned by a spring, for example, is provided which opens when the cooling oil pressure downstream of the oil cooler 600 exceeds a predetermined pressure threshold and lets the cooling oil past the oil cooler 600 to the dual clutch.

[0114] As was already stated, a comparatively small volume flow at relatively high pressure is needed to actuate the actuation piston of the two clutch devices 204 b and 206 b. Consequently, the pump 208 b which is driven by electric motor is preferably a hydrostatic pump, e.g., a toothed gear pump or vane cell pump.

[0115] In the embodiment example in FIG. 12, a pressure oil storage 604 having a gas cushion under pressure is installed in the clutch actuation pressure oil circuit and is charged by the pump 208 b via a non-return valve 606 and is connected via valve 214 b and valve 216 b to the actuation slave cylinders of the two clutch devices 204 b and 206 b. The pressure oil storage 604 provides for a uniform pressure level which is particularly advisable in case the pump 208 b is constructed as a piston pump and allows a pump with a particularly small conveying volume to be used as pump 208 b. Thus, the oil volume delivered by the pump 208 b per time unit can be less than the pressure oil volume required per time unit during actuation of the clutch.

[0116] The pressure oil circuit between the non-return valve 606 and the valves 214 b and 216 b is protected against excessively high pressure of the pressure oil which could possibly result in damage by means of a pressure limiting valve 608. The pressure determined by the fluid level of the storage 604 is detected by a pressure sensor 610 in this pressure oil circuit.

[0117] Another pressure limiting valve 612 ensures that the pressure prevailing on the other side of the valves 214 b and 216 b and acting on the hydraulic slave cylinders of the clutch devices does not exceed a maximum value, for example, in order to prevent possible damage. Due to two non-return valves 614 and 616, one pressure limiting valve is sufficient for monitoring the actuation pressure of two hydraulic slave cylinders.

[0118] In case the pressure of the cooling oil is not sufficient to cool the clutch at low temperatures, that is, in case of high oil viscosity, for example because the hydrodynamic pump used for pump 209 b can not generate sufficient pressure, a valve 614 is provided in the arrangement according to FIG. 12, through which valve 614 a small volume flow can be branched off from the cooling oil flow supplied by the pump 208 b in order to provide a kind of “emergency cooling” of the clutch arrangements when required. Since the high viscosity of the cooling oil which makes it necessary to open the valve 614 occurs only at low temperatures at which there is only a low cooling requirement for the dual clutch in any case, a relatively small “emergency cooling oil flow” is sufficient. Moreover, this emergency cooling is only required until the temperature of the oil and, accordingly, the viscosity of the oil is sufficient to ensure adequate pumping output of the cooling oil pump 209 b. Instead of a valve 614, a diaphragm or choke or the like could also be provided by which a small volume flow is continuously branched off from the pressure oil flow supplied by the pump 208 b in the cooling circuit. When using the valve 614 which branches off the cooling oil only in case of need, the pump 208 b can possibly also be operated briefly in overload operation in order to supply sufficient cooling oil within the short time period before the oil is sufficiently heated. Since the time periods when this is required are generally only very short, the life of the pump 208 b is not substantially shortened in this way.

[0119]FIG. 13 shows a dual clutch 12 arranged in a drivetrain 10 between a drive unit and a transmission. The only part of the drive unit, e.g., an internal combustion engine, shown in FIG. 13 is a driven shaft 14, possibly a crankshaft 14, with a coupling end 16 serving to couple a torsional vibration damper, not shown. The transmission is represented in FIG. 13 by a transmission housing portion 20 defining a transmission housing casing 18 and two transmission input shafts 22 and 24, both of which are constructed as hollow shafts. Transmission input shaft 22 extends through transmission input shaft 24 essentially coaxial thereto. A pump drive shaft which serves to drive an oil pump on the transmission side, not shown in FIG. 13, is arranged in the interior of the transmission input shaft 22 as will be discussed further. When at least one oil pump driven by electric motor is provided, the pump drive shaft can be dispensed with.

[0120] The dual clutch 12 is received in the transmission housing casing 18, wherein the interior of the casing is closed in the direction of the drive unit by a cover 28 which is pressed into a casing housing opening and/or is secured therein by a snap ring 30. When the dual clutch has wet friction clutches, for example, disk clutches, as in the embodiment example shown in FIG. 13, it is generally arranged so as to ensure a tight engagement between the cover 28 and the clutch housing formed by the transmission housing casing 18. This tight engagement can be produced, for example, by means of an O-ring or some other sealing ring. FIG. 13 shows a sealing ring 32 with two sealing lips.

[0121] A clutch hub 34 comprising two annular portions 36, 38 secured to one another for reasons which will be explained in the following serves as input side of the dual clutch 12. The clutch hub 34 extends through a central opening of the cover 28 in the direction of the drive unit and is coupled via an external toothing 42 with the torsional vibration damper, not shown, so that there is a torque-transmitting connection between the coupling end 16 of the crankshaft 14 and the coupling hub 34 by means of this torsional-vibration damper. If a torsional vibration damper is not desired at this location in the drivetrain, or at all, the clutch hub 34 can also be coupled directly to the coupling end 16. The pump drive shaft 26 has an external toothing 44 at its end remote of the transmission which engages in an internal toothing 46 of the annular portion 36 of the clutch hub 34, so that the pump drive shaft 26 rotates along with the clutch hub 34 and accordingly drives the oil pump when a rotational movement is imparted to the clutch hub 34, generally by the drive unit and in many operating situations possibly also by the transmission via the dual clutch (for example, in an operating situation characterized by the term “engine braking”).

[0122] The cover 28 extends radially between an annular circumferential wall portion of the housing casing 18 defining a radial recess 50 of the housing casing 18 and the annular portion 38 of the hub 34. It is advantageous when a seal arrangement and/or pivot bearing arrangement 54 is provided between a radial inner wall area 52 of the cover 28 and the hub 34, especially the annular portion 38, especially when—as in the illustrated embodiment example—the cover 28 is secured to the housing casing 18 and therefore does not rotate along with the dual clutch 12. A seal between the cover and the hub is required particularly when the clutch arrangements of the dual clutch are wet clutches as in the embodiment example. Highly reliable operation is also achieved in case of occurring oscillations and vibrations when the seal arrangement and/or pivot bearing arrangement 54 are/is secured axially at the cover 28 and/or at the clutch hub 34, for example, by an end portion of the cover edge 52 that is bent radially inward, as is shown in FIG. 13.

[0123] A support plate 60 which serves to transmit torque between the hub 34 and an outer disk carrier 62 of a first multi-disk clutch arrangement 64 is arranged at the annular portion 38 of the hub 34 so as to be fixed with respect to rotation relative to it. Referring to the arrangements according to FIGS. 1, 9, 11 and 12, the multi-disk clutch arrangement can be identified, for example, as clutch arrangement 204, 204 a or 204 b. The outer disk carrier 62 extends in the direction of the transmission and radially inward to an annular part 66 at which the outer disk carrier is arranged so as to be fixed with respect to rotation relative to it and which is rotatably supported at the two transmission input shafts 22 and 24 by means of an axial and radial bearing arrangement 68 in such a way that radial as well as axial forces are supported at the transmission input shafts. The axial and radial bearing arrangement 68 makes possible a relative rotation between the annular part 66 on the one hand and transmission input shaft 22 and transmission input shaft 24 on the other hand. The construction and operation of the axial and radial bearing arrangement will be discussed more fully later on.

[0124] An outer disk carrier 70 of a second multi-disk clutch arrangement 72 is arranged at the annular part 66 farther axially in the direction of the drive unit so as to be fixed with respect to rotation relative to it, its disk stack 74 being surrounded annularly by the disk stack 76 of the first multi-disk clutch arrangement. Referring to the arrangements shown in FIGS. 1, 9, 11 and 12, the second multi-disk clutch arrangement can be identified, for example, as clutch arrangement 204, 204 a or 204 b. As was already indicated, the two outer disk carriers 62 and 70 are connected with one another by the annular part 66 so as to be fixed with respect to relative rotation and are jointly in a torque-transmitting connection with the clutch hub 34 and therefore—via the torsional vibration damper, not shown—with the crankshaft 14 of the drive unit by means of the carrier plate 60 which is in a positive-locking torque-transmitting engagement with the outer disk carrier 62 by means of an external toothing. Referring to the normal flow of torque from the drive unit to the transmission, the outer disk carriers 62 and 70 serve as input side of the multi-disk clutch arrangement 64 and 72, respectively.

[0125] A hub part 80 of an inner disk carrier 82 of the first multi-disk clutch arrangement 64 is arranged on the transmission input shaft 22 so as to be fixed with respect to rotation relative to it by means of a spline or the like. In a corresponding manner, a hub part 84 of an inner disk carrier 86 of the second multi-disk clutch arrangement 72 is arranged on the radial outer transmission input shaft 24 so as to be fixed with respect to rotation relative to it by means of a spline or the like. Referring to the regulating torque flow from the drive unit in the direction of the transmission, the inner disk carriers 82 and 86 serve as output side of the first and second multi-disk clutch arrangements 64 and 72.

[0126] Referring again to the radial and axial bearing support of the annular part 66 at the transmission input shafts 22 and 24, two radial bearing subassemblies 90 and 92 acting between the radial outer transmission input shaft 24 and the annular part 66 serve as radial support of the annular part 66. With regard to a support in the direction of the drive unit, the axial bearing support of the annular part 66 is carried out by means of hub part 84, an axial bearing 94, hub part 80 and a snap ring 96 which secures the hub part 80 axially to the radial inner transmission input shaft 22. The annular part 38 of the clutch hub 34 is supported in turn via an axial bearing 68 and a radial bearing 100 at the hub part 80. The hub part 80 is supported axially in the direction of the transmission at an end portion of the radial outer transmission input shaft 24 by the axial bearing 94. Hub part 84 can be supported at the transmission input shaft 24 directly at an annular stop or the like or at a separate snap ring or the like in the direction of the transmission. Since the hub part 84 and the annular part 66 are rotatable relative to one another, an axial bearing can be provided between these components insofar as the bearing 92 does not function as both axial bearing and radial bearing. The latter is assumed with regard to the embodiment example in FIG. 13.

[0127] Great advantages result when, as in the present embodiment example, the portions of the outer disk carriers 62 and 70 extending in radial direction are arranged on one axial side of a radial plane extending orthogonal to an axis A of the dual clutch 12 and the portions of the inner disk carriers 82 and 86 of the two multi-disk clutch arrangements extending in radial direction are arranged on the other axial side of this radial plane. This allows a particularly compact construction, particularly when—as in the present embodiment example—disk carriers of one type (outer disk carrier as in the embodiment example or inner disk carrier) are connected with one another so as to be fixed with respect to relative rotation and serve in each instance as the input side of the respective multi-disk clutch arrangement with respect to the flow of force from the drive unit to the transmission.

[0128] Actuation pistons for actuating the multi-disk clutch arrangements are integrated in the dual clutch 12 in order to actuate the multi-disk clutch arrangements for engagement in the case of the present embodiment example. An actuation piston 110 associated with the first multi-disk clutch arrangement 64 is arranged axially between the radially extending portion of the outer disk carrier 62 of the first multi-disk clutch arrangement 64 and the radially extending portion of the outer disk carrier 70 of the second multi-disk clutch arrangement 72 and is guided so as to be axially displaceable at both outer disk carriers and at the annular portion 66 by means of seals 112, 114, 116 and so as to seal a pressure chamber 118 formed between the outer disk carrier 62 and the actuation piston 110 and a centrifugal force pressure compensation chamber 120 formed between the actuation piston 110 and the outer disk carrier 70. The pressure chamber 118 communicates, via a pressure medium channel 122 formed in the annular portion 66, with a pressure control device, possibly a control valve (possibly valve 214, 214 a or 214 b) which is connected to a pressure medium supply, possibly the oil pump already mentioned above or pump 208 or 208 b or component P (220 a). The pressure medium channel 122 is connected to the pressure control device via a connection sleeve which receives the annular part 66 and which is possibly fixed with respect to the transmission. With regard to the annular part 66, it should be noted in this connection that for purposes of a simpler manufacture particularly with respect to the pressure medium channel 122 and another pressure medium channel this annular part 66 is produced in two parts with two sleeve-like ring part segments which are inserted one into the other as is shown in FIG. 13.

[0129] An actuation piston 130 associated with the second multi-disk clutch arrangement 72 is arranged axially between the outer disk carrier 70 of the second multi-disk clutch arrangement 72 and a substantially radially extending wall part 132 arranged at an axial end region of the annular part 66 remote of the transmission so as to be fixed with respect to rotation relative to it and so as to be tight against fluid and is guided so as to be axially displaceable by means of seals 134, 136 and 138 at the outer disk carrier 70, the wall part 132 and the annular part 66 and so as to seal a pressure chamber 140 formed between the outer disk carrier 70 and the actuation piston 130 and a centrifugal force pressure compensation chamber 142 formed between the actuation piston 130 and the wall part 132. The pressure chamber 140 is connected via another pressure medium channel 144 (already mentioned) in a manner corresponding to pressure chamber 118 at a/the pressure control device (possibly valve 216, 216 a or 216 b in connection with the pump 208 or pump 208 b or component P (220 a)). Pressure applied by the (respective) pressure medium source (possibly oil pump) can be applied to the two pressure chambers 118 and 140 selectively (possibly also simultaneously) by means of the pressure control device(s) in order to actuate the first multi-disk clutch arrangement 64 and/or the second multi-disk clutch arrangement 72 for purpose of engagement. Diaphragm springs 146, 148 serve to restore, that is, to release, the clutches; the diaphragm spring 148 associated with the actuation piston 130 is received in the centrifugal force pressure compensation chamber 142.

[0130] The pressure chambers 118 and 140 are completely filled with pressure medium (in this case hydraulic oil) in every case during normal operating states of the dual clutch 12 and the actuating state of the multi-disk clutch arrangements, per se, depends on the pressure of the pressure medium applied to the pressure chambers. However, since the outer disk carriers 62 and 70, including the annular part 66 and the actuation piston 110 and 130 and the wall part 132, rotate together with the crankshaft 14 in driving operation, pressure increases in the pressure chambers 118 and 140 which are caused by centrifugal force are brought about even when no pressure is applied to the pressure chambers on the part of the pressure control device, which increases could lead to an unwanted engagement or at least slippage of the multi-disk clutch arrangements at least at higher rotational speeds. The centrifugal force pressure compensation chambers 120, 142, already mentioned, which receive a pressure compensation medium and in which pressure increases occur correspondingly as a result of centrifugal force, which pressure increases compensate for the pressure increases caused in the pressure chambers by centrifugal force, are provided for this reason.

[0131] It is also possible to fill the centrifugal force pressure compensation chambers 120 and 142 permanently with pressure compensation medium, for example, oil, wherein, as the case may be, a volume compensation could be provided to absorb pressure compensation medium displaced in the course of actuating the actuation pistons. In the embodiment form shown in FIG. 13, the centrifugal force pressure compensation chambers 120, 142 are first filled with pressure compensation medium during operation of the drivetrain, specifically in connection with the supply of cooling fluid, particularly cooling oil in the shown embodiment example, to the multi-disk clutch arrangements 64 and 72 via an annular channel 150 formed between the annular part 66 and the outer transmission input shaft 24, with which the bearings 90, 92 which pass the cooling oil are associated. The cooling oil which is supplied, as the case may be, by component P (220) or pump 208 a or 209 b flows from a transmission-side connection between the annular part and the transmission input shaft 24 in the direction of the drive unit through bearing 90 and bearing 92 and then flows in a partial flow between the end portion of the annular part 66 remote of the transmission and the hub part 84 radially outward in the direction of the disk stack 74 of the second multi-disk clutch arrangement 72, enters the area of the disks through the passages in the inner disk carrier 86, flows radially outward between the disks of the disk stack 74 and through friction lining grooves, or the like, of these disks, enters the area of the disk stack 76 of the first multi-disk clutch arrangement 64 through passages in the outer disk carrier 70 and through passages in the inner disk carrier 82, flows radially outward between the disks of this disk stack and through lining grooves, or the like, in these disks and then, finally, flows off radially outward through passages in the outer disk carrier 62. The centrifugal force pressure compensation chambers 120, 142 are also connected to the cooling oil supply between the annular part 66 and the transmission input shaft 24, specifically by means of radial bore holes 152, 154 in the annular part 66. Due to the fact that the cooling oil serving as pressure compensation medium in the pressure compensation chambers 120, 142 flows off out of the pressure compensation chambers due to the absence of centrifugal force when the drive unit is stationary, the pressure compensation chambers are refilled again during the operation of the drivetrain (of the motor vehicle).

[0132] Since a pressure application surface of the actuation piston 130 associated with the pressure chamber 140 is smaller and also does not extend as far radially outward as a pressure application surface of the piston 130 associated with the pressure compensation chamber 142, at least one fluid level limiting opening 156 is formed in the wall part 132 and adjusts a maximum radial fluid level of the pressure compensation chamber 142 providing the required centrifugal force compensation. When the maximum fluid level is reached, the cooling oil supplied via the bore hole 154 flows off through the fluid level limiting opening 156 and combines with the cooling oil flowing radially outward between the annular part 66 and the hub part 84. In the case of the piston 110, the pressure application surfaces of the piston which are associated with the pressure chamber 118 and the pressure application surfaces of the piston which are associated with the pressure compensation chamber 120 are of the same size and extend in the same radial area so that corresponding fluid level limiting means are not required for the pressure compensation chamber 120.

[0133] For the sake of completeness, it should be noted that additional cooling oil flows preferably occur in operation. Accordingly, at least one radial bore hole 160 is provided in the transmission input shaft 24, a further partial flow of cooling oil flows via this radial bore hole 160 and via an annular channel between the two transmission input shafts and splits into two partial flows, one of which flows radially outward between the two hub parts 80 and 84 (through the axial bearing 94) and the other partial flow flows radially outward between the end area of the transmission input shaft 22 remote of the transmission and the hub part 80 and between this hub part 80 and the annular portion 38 of the clutch hub 34 (through the bearings 98 and 100).

[0134] Since the cooling oil flowing radially outward could collect in the neighborhood of a radial outward portion of the actuation piston 110 associated with the first multi-disk clutch arrangement 64 and could hinder the engaging movement of the piston 110 due to centrifugal force at least at higher rotational speeds, this piston 110 has at least one pressure compensation opening 162 which enables cooling oil to flow from one side of the piston to the other. Consequently, a collection of cooling oil can come about on both sides of the piston with corresponding compensation of pressure forces exerted on the piston as a result of centrifugal force. Further, other forces based on an interaction between the cooling oil and the piston are prevented from hindering the required axial piston movements. By this is meant, for example, hydrodynamic forces or the like, as well as the piston attaching itself by suction to the outer disk carrier 62.

[0135] It is also possible to provide at least one cooling oil flow-off opening in the radially extending, radial outer area of the outer disk carrier 62 of the first multi-disk clutch arrangement 64. A cooling oil flow-off opening of this kind is indicated by dashed lines at 164. In order nevertheless to ensure a sufficient flow of cooling fluid (cooling oil) through the disk stack 76 of the first multi-disk clutch arrangement 64, a cooling oil conducting element (generally a cooling fluid conducting element) can be provided. It is indicated in dashed lines in FIG. 13 that an adjoining end disk 166 of the disk stack 76 could have a cooling oil conducting portion 168, so that the end disk 166 itself serves as cooling oil conducting element.

[0136] For the purpose of a simple construction of the pressure control device for actuation of the two multi-disk clutch arrangements, it was provided in the embodiment example in FIG. 13 that a torque transmission capability which is given per se for the radial inner multi-disk clutch arrangement 72 with respect to an actuation pressure and which is smaller (because of a smaller effective friction radius than the radial outer clutch arrangement 64) compared to the other clutch arrangement 64 is at least partially compensated. For this purpose, the pressure application surface of the piston 130 associated with the pressure chamber 140 is greater than the pressure application surface of the piston 110 associated with the pressure chamber 118, so that the axially directed forces acting on piston 130 are greater than those exerted on piston 110 at the same hydraulic oil pressure in the pressure chambers.

[0137] It should be mentioned that it is possible to make good use of the available installation space by means of a radial offsetting of the seals associated with the piston, especially also an axial overlapping of at least some of the seals.

[0138] Steps for preventing the risk of overheating can be taken with the disk stacks 74, 76 in addition to the supply of cooling oil already described and the forming of cooling oil passages (only shown schematically in FIG. 13) in the disk carriers. Accordingly, it is advantageous to use at least some of the disks as “heat buffers” which temporarily store heat which occurs, for example, during slip operation and which momentarily overburdens the possibilities for heat flow-off by means of the cooling fluid (in this case cooling oil) or by means of heat conduction via the disk carriers, so that the heat can be guided off subsequently, for example, in a disengaged state of the respective multi-disk clutch arrangement. For this purpose, disks without friction linings in the radial inner (second) multi-disk clutch arrangement are constructed so as to be thicker axially than friction lining carrying elements of disks carrying friction linings in order to provide a comparatively large material volume with corresponding heat capacity for the disks without friction linings. These disks should be produced from a material having a considerable heat storage capability (heat capacity), for example, steel. When using conventional friction linings made of paper, for example, the friction lining carrying disks can only store a little heat intermediately, since paper has a poor thermal conductivity.

[0139] The heat capacity of the friction lining carrying elements carrying the friction linings can likewise be made available as a heat accumulator when lining materials with high conductivity are used instead of lining materials with low conductivity. The use of friction linings of sintered material having a comparatively high heat conductivity is possible. However, the use of sintered linings is problematic in that sintered linings have a degressive curve of the friction coefficient over a slippage speed (relative rotational speed N between the rubbing surfaces), that is, in that d/d N<0. A degressive curve of the friction coefficient is disadvantageous insofar as this can promote a self-excitation of vibrations in the drivetrain or at least can not dampen vibrations. Therefore, it is advantageous when disks with friction linings of sintered material as well as disks with friction linings of another material with a progressive friction coefficient curve over the slippage speed (d/d N>0) are provided in a disk stack, so that a progressive friction coefficient curve over the slippage speed or at least approximately a neutral friction coefficient curve over the slippage speed (d/d N=0) results on the whole for the disk stack and consequently a self-excitation of vibrations in the drivetrain is at least not promoted or—preferably rotational vibrations in the drivetrain are even damped (because of a considerable progressive friction coefficient curve over the slippage speed).

[0140] It is assumed that in the embodiment example of FIG. 13, the disk stack 74 of the radial inner multi-disk clutch arrangement 72 is constructed without sintered linings since the radial outer multi-disk clutch arrangement 64 is preferably used as starting clutch with corresponding slippage operation. The latter, that is the use of the radial outer multi-disk clutch arrangement as a starting clutch, is advantageous insofar as this multi-disk clutch arrangement can be operated with smaller actuation forces (for the same torque transmission capability) because of the greater effective friction radius, so that surface pressing can be reduced compared to the second multi-disk clutch arrangement. It is also helpful in this respect when the disks of the first multi-disk clutch arrangement 64 are formed with a somewhat greater radial height than the disks of the second multi-disk clutch arrangement 72. If desired, however, friction linings of sintered material can also be used for the disk stack 74 of the radial inner (second) multi-disk clutch arrangement 72, preferably—as mentioned—in combination with friction linings from another material such as paper.

[0141] While all inner disks carry a friction lining and all outer disks are disks without linings in the disk stack 74 of the radial inner multi-disk clutch arrangement 72, wherein the end disks defining the disk stack axially are outer disks and are accordingly disks without lining, the inner disks in the disk stack 76 of the first multi-disk clutch arrangement 64 are disks without linings and the outer disks, including the end disks 166, 170, are disks carrying friction linings. According to a preferred construction, at least the end disks 166 and 170 have lining carrying elements which are substantially thicker axially than the lining carrying elements of the other outer disks and are constructed with linings of sintered material in order to make the lining-carrying elements of the two end disks having a comparatively large volume usable as heat buffers. As in the disk stack 74, the disks without linings are axially thicker than the friction lining carrying elements of the disks carrying friction linings (with the exception of the end disks) in order to provide a comparatively large heat capacity for temporary storage of heat. The outer disks located on the axial inner side should have, at least in part, friction linings of another material exhibiting a progressive friction coefficient curve in order to achieve at least an approximately neutral friction coefficient curve over the slippage rotation speed for the disk stack in its entirety.

[0142] The person skilled in the art can easily gather further details of the dual clutch 12 according to the described embodiment example from FIG. 13. Accordingly, the axial bore hole in the annular portion 36 of the clutch hub 34 in which the internal toothing 46 for the pump drive shaft is formed is closed in an oil-tight manner by a stopper 180 which is held therein. The carrier plate 60 is fixed axially at the outer disk carrier 62 by two retaining rings 172, 174, the retaining ring 172 also supports the end disk 170 axially. A corresponding retaining ring is also provided for supporting the disk stack 74 at the outer disk carrier 70.

[0143]FIG. 14 shows a rotor device 700 which can be used as component P (220) in the arrangement according to FIG. 1 or as component P (220 a) of the arrangement according to FIG. 9. Referring to the application depicted in FIG. 1, the rotor device has at least one pressure medium connection 702 connected to the pump 208 via the valve 218 or directly and a cooling oil connection 703 which is connected to the reservoir 222 and from which cooling oil can flow, possibly via a non-return valve, not shown, into a housing 706 of the rotor device 700 constructed in multiple parts to two conveying rotors 708 a and 708 b which have conveying geometries in the form of toothings meshing with one another. The two conveying rotors 708 a and 708 b form an external toothed gear pump.

[0144] Pressure oil flowing into the housing 706 via the connection 702 strikes two drive rotors 710 a and 710 b which have meshing drive geometries in the form of toothings and are set in rotation by the pressure oil. The two drive rotors form a hydromotor 710 in a rotary positive-displacement type construction, especially an external toothed gear motor. The drive rotor 710 a is connected with the conveying rotor 708 a so as to be fixed with respect to rotation relative to it and the drive rotor 710 b is connected with the conveying rotor 708 b so as to be fixed with respect to rotation relative to it. The cooling oil conveyed by the conveying rotors 708 a and 708 b flows over a flow-off channel 716 in the direction of the dual clutch 202 in order to supply the disk clutches 204 and 206 with cooling oil. The pressure oil which has passed the drive rotors 710 a and 710 b flows off via a channel 717 which preferably passes into the channel 716.

[0145] As is shown in FIG. 14, the drive rotor 710 a and the conveying rotor 708 a have a common rotating shaft, e.g., such that two toothed gears are cut into a rotating shaft. The same can apply to the drive rotor 710 b and the conveying rotor 708 b as is shown in FIG. 14. As was mentioned, the pair of rotors (possibly a pair of toothed gears) 710 a, 710 b are driven by the pump 208, preferably a hydrostatic pump. Since the rotor pair (possibly a toothed gear pair) 708 a, 708 b is located on the same shaft with a respective drive rotor and, as can be seen in FIG. 14, is longer axially (has teeth which are wider axially) than the drive rotors, a larger volume flow can be conveyed at a lower pressure. According to FIG. 14, the two pairs of rotors and therefore the volume flows (pressure oil volume flow and cooling oil volume flow) are separated from one another by a divided separating or sealing disk 721. The sealing disk is shown in FIG. 17 and comprises two half disks 721 a and 721 b which define two openings 723 a and 723 b for the rotor shafts 725 a and 725 b in the assembled state.

[0146] Another embodiment form of a rotor device 800 functioning according to the same principle is shown schematically in FIG. 18. In this case, the drive rotors 810 a and 810 b of the hydromotor 810 have a smaller diameter than the conveying rotors 808 a and 808 b, so that a volume flow which is greater than a pressure oil flow driving the drive rotors 810 a and 810 b can be conveyed again by means of the conveying rotors but, on the other hand, has a lower pressure than this flow of pressure oil. The drive rotor 810 a and the conveying rotor 808 a have a common rotating shaft 825 a. The drive rotor 810 b and the conveying rotor 808 b have their own rotating shaft 825 b and 825 c, respectively. These two rotors 810 b and 808 b are in a drive connection, via their toothings meshing with the toothings of the rotors 810 a and 808 a, with these rotors, that is, rotors 810 a and 808 a.

[0147] To summarize, the invention is directed to a clutch system comprising at least one clutch device particularly for arrangement in a drivetrain between a drive unit and a transmission. The clutch device can be actuated through the intermediary of pressure medium and/or provided for operation under the influence of an operating medium. According to one aspect of the invention, it is suggested that a secondary medium serving as pressure medium for actuation or serving as operating medium for the operation of the clutch arrangement can be supplied by means of a pump arrangement supplying a primary medium and by means of a secondary medium supply arrangement or secondary pump arrangement connected to the pump arrangement, wherein the secondary medium supply arrangement or secondary pump arrangement has at least one pressure receiving element which is arranged so as to be movable in a housing and which is exposed at least on at least one pressure receiving surface in operation with the primary medium supplied by the first pump arrangement, which pressure receiving element is set in motion through the intermediary of the operating medium, and at least one interacting element which is arranged in the/a housing so as to be movable, is coupled with respect to movement with the pressure receiving element and interacts in operation with the secondary medium at least on at least one interaction surface, the secondary medium can be supplied by means of this interaction element possibly through displacement and/or imparting an acceleration and/or imparting angular momentum or swirl. 

1. Clutch system comprising at least one clutch device, particularly for arrangement in a drivetrain between a drive unit and a transmission, wherein the clutch device (202) has at least one clutch arrangement (204, 206) which is provided for operation under the action of an operating medium, operating medium can be supplied to the clutch arrangement (204, 206) for this operation by means of a pump arrangement (208) supplying pressure medium and an operating medium supply arrangement (220) which is connected to the pump arrangement and which provides the operating medium in a flow of operating medium with reduced pressure relative to a pressure medium whose pressure is given by the pump arrangement (208) and, in relation to the medium volume supplied per time unit averaged over time, the operating medium flow is greater than a pressure medium flow possibly flowing from the pump arrangement (208) to the operating medium supply arrangement (202), wherein the operating medium supply arrangement has at least one pressure receiving element (234; 310; 410) which is arranged so as to be movable in a housing (232; 306; 402) and which is exposed at least on at least one pressure receiving surface to the pressure medium which is provided by the pump arrangement (208) in operation and can be set in motion through the intermediary of the pressure medium, and at least one interaction element (234; 308; 408) which is arranged so as to be movable in the housing or a housing (232; 306; 402) and which is coupled with respect to movement with the pressure receiving element and interacts during operation with the operating medium at least on at least one interaction surface, and the operating medium flow can be supplied through the intermediary of this interaction element (234; 308; 408).
 2. Clutch system according to claim 1, characterized in that the operating medium supply arrangement (220) is connected to an operating medium reservoir (222) and can draw operating medium from the latter to supply to the clutch arrangement (204, 206).
 3. Clutch system according to claim 1 or 2, characterized in that the operating medium supply arrangement (220) is constructed as a pressure converter arrangement (230; 300; 400).
 4. Clutch system according to one of claims 1 to 3, characterized in that the effective surface of the pressure receiving surface exposed to the pressure medium is smaller per time unit averaged over time than the effective surface of the interaction surface interacting with the operating medium.
 5. Clutch system according to one of claims 1 to 4, characterized in that at least one component (234) is provided which is constructed integrally or in one piece and which forms the/a pressure receiving element or the/a interaction element.
 6. Clutch system according to claim 5, characterized in that the component is constructed as a piston (234) arranged in a piston housing (232) so as to be displaceable along an axis with a first piston surface (262) exposed to the pressure medium and a second piston surface (280) interacting with the operating medium, the first piston surface (262) serving as a pressure receiving surface and the second piston surface (280) serving as an interaction surface, wherein the piston surfaces are arranged at opposite axial end faces of the piston, and the first piston surface is preferably smaller than the second piston surface.
 7. Clutch system according to one of claims 1 to 5, characterized in that at least one rotor component (310 or 308; 410 or 408) forms the pressure receiving element and/or the interaction element.
 8. Clutch system according to one of claims 1 to 7, characterized in that the operating medium supply arrangement (220) comprises a pump arrangement or is identifiable as a pump arrangement.
 9. Clutch system according to one of claims 1 to 8, characterized in that the clutch device (204, 206) can be actuated through the intermediary of the pressure medium supplied by the pump arrangement (208).
 10. Clutch system comprising at least one clutch device particularly for arrangement in a drivetrain (particularly in a motor vehicle) between a drive unit and a transmission, wherein the clutch device (202 a) has at least one clutch arrangement (204 a, 206 a) which can be actuated through the intermediary of pressure medium, wherein the pressure medium can be supplied for the actuation based on a pump arrangement (208 a) supplying an operating medium and based on a pressure medium supply arrangement (220 a) which is connected to the pump arrangement and which supplies the pressure medium at a pressure that is increased relative to a pressure of the operating medium that is given by the pump arrangement (208 a), and possibly in a flow of pressure medium which, with respect to medium volume supplied per time unit averaged over time, is smaller than an operating medium flow possibly flowing from the pump arrangement (208 a) to the pressure medium supply arrangement (220 a), wherein the pressure medium supply arrangement has at least one pressure receiving element (534) which is arranged so as to be movable in a housing (532) and which is exposed in operation at least on at least one pressure receiving surface to operating medium supplied by the pump arrangement (208 a) and can be set in motion through the intermediary of the operating medium, and at least one interaction element (534) which is arranged so as to be movable in the/a housing (532) and which is coupled with respect to movement with the pressure receiving element and interacts during operation with the pressure medium at least on at least one interaction surface, and the pressure medium can be supplied through the intermediary of the interaction element.
 11. Clutch system according to claim 10, characterized in that the pressure medium supply arrangement (220 a) is connected to a medium reservoir (212 a) and draws medium from the latter to supply the clutch arrangement (204 a, 206 a) and/or conducts medium away to the medium reservoir (212 a).
 12. Clutch system according to claim 10 or 11, characterized in that the pressure medium supply arrangement (220 a) is constructed as a pressure converter arrangement (500).
 13. Clutch system according to one of claims 10 to 12, characterized in that the effective area of the pressure receiving surface exposed to the operating medium is larger per time unit averaged over time than the effective area of the interaction surface interacting with the pressure medium.
 14. Clutch system according to one of claims 10 to 14, characterized in that at least one component (534) is provided which is constructed integrally or in one piece and which forms the/a pressure receiving element and the/an interaction element.
 15. Clutch system according to claim 14, characterized in that the component is constructed as a piston (534) arranged in a piston housing so as to be displaceable along an axis with a first piston surface (526) which serves as a pressure receiving element and which is exposed to the operating medium and a second piston surface (580) interacting with the pressure medium which serves as interaction surface, wherein the piston surfaces are arranged at opposite axial end areas of the piston and the first piston surface is preferably larger than the second piston surface.
 16. Clutch system according to one of claims 10 to 15, characterized in that at least one rotor component forms the pressure receiving element and/or the interaction element.
 17. Clutch system according to one of claims 10 to 16, characterized in that the pressure medium supply arrangement (220 a) comprises a pump arrangement or can be identified as a pump arrangement.
 18. Clutch system according to one of claims 10 to 17, characterized in that the clutch device (202 a) is provided for operation under the influence of an operating medium which can be supplied to the clutch device (202 a) by the pump arrangement (208 a) for this operation.
 19. Clutch system according to one of claims 1 to 18, characterized in that a hydraulic medium is used as operating medium and as pressure medium.
 20. Clutch system comprising at least one clutch device particularly for arrangement in a drivetrain between a drive unit and a transmission, wherein the clutch device (202) has at least one clutch arrangement (204, 206) which is provided for operation under the influence of an operating medium and to which operating medium can be supplied for this operation based on a first pump arrangement (208) (also referred to hereinafter as primary pump arrangement) which supplies pressure medium and a second pump arrangement (220) (also referred to hereinafter as secondary pump arrangement) which is connected to the first pump arrangement and which can be driven by the pressure medium supplied by the first pump arrangement, wherein the secondary pump arrangement (220) has at least one pump element (234; 310; 410) which is arranged so as to be movable in a housing (232; 306; 402), can be driven through the intermediary of the pressure medium (also referred to hereinafter as primary medium), interacts with the operating medium (also referred to hereinafter as secondary medium), and conveys the secondary medium (operating medium) during operation by means of displacement and/or by imparting an acceleration and/or by imparting swirl in the direction of the clutch arrangement.
 21. Clutch system comprising at least one clutch device particularly for arrangement in a drivetrain between a drive unit and a transmission, wherein the clutch device (202 a) has at least one clutch arrangement (204 a, 206 a) which can be actuated through the intermediary of pressure medium, wherein the pressure medium can be supplied for this actuation based on a second pump arrangement (208 a) (also referred to hereinafter as primary pump arrangement) supplying operating medium and a first pump arrangement (220 a) (also referred to hereinafter as secondary pump arrangement) which is connected to the second pump arrangement and can be driven by the operating medium supplied by the second pump arrangement, wherein the secondary pump arrangement (220 a) has at least one pump element (534) which is arranged so as to be movable in a housing, can be driven through the intermediary of the operating medium (also referred to hereinafter as primary medium), interacts with the pressure medium (also referred to hereinafter as secondary medium) and, during operation, brings the secondary medium (pressure medium) to a pressure sufficient for clutch actuation by means of displacement and/or imparting an acceleration and/or imparting a swirl.
 22. Clutch system according to claim 20 or 21, characterized in that the secondary pump arrangement (220; 208 a) is connected to an operating medium reservoir and can draw operating medium from the latter for supplying to the clutch arrangement.
 23. Clutch system according to one of claims 20 to 22, characterized in that the second pump arrangement (220; 208 a) supplies the operating medium in a operating medium flow which has a lower pressure than a pressure of the pressure medium that is given by the first pump arrangement (208; 220 a) and which, with respect to the medium volume supplied per time unit averaged over time, is greater than pressure medium flow possibly flowing from the first pump arrangement to the second pump arrangement or which can be supplied in its entirety in continuous operation by the pump arrangement.
 24. Clutch system according to one of claims 20 to 23, characterized in that the primary pump arrangement (208; 208 a) can be driven electrically and/or through the intermediary of the drive unit and/or the transmission.
 25. Clutch system according to one of claims 20 to 24, characterized in that at least one of the first and second pump arrangements comprises at least one hydrostatic pump or a pump constructed as a positive-displacement machine.
 26. Clutch system according to claim 25, characterized in that the first pump arrangement (208; 220 a) has at least one hydrostatic pump or pump (500) constructed as a positive-displacement machine.
 27. Clutch system according to one of claims 20 to 26, characterized in that at least one of the first and second pump arrangements comprises at least one hydrodynamic pump or a pump constructed as a liquid flow machine.
 28. Clutch system according to claim 27, characterized in that the second pump arrangement (220; 208 a) has at least one hydrodynamic pump, or pump (300; 400) constructed as a flow machine, that can be driven by pressure medium supplied by the first pump arrangement.
 29. Clutch system according to one of claims 25 to 28, characterized in that the pump has at least one pump element (234; 308; 408; 534) that can be driven in a translational or rotational manner and which can be driven by a motor, particularly an electric motor, in the case of a pump associated with the primary pump arrangement (208; 208 a) or which can be driven through the intermediary of the primary medium in case of a pump associated with the secondary pump arrangement (220; 220 a).
 30. Clutch system according to one of claims 20 to 29, characterized in that the secondary pump arrangement has at least one piston pump (230; 500) that can be driven by the primary medium supplied by the primary pump arrangement.
 31. Clutch system according to claim 30, characterized in that the piston pump (230; 500) has at least one piston (234; 534) which is arranged in a pump housing so as to be displaceable along an axis and with a first piston surface (262; 562) exposed to the primary medium and a second piston surface (280; 580) interacting with the secondary medium, wherein the piston surfaces are arranged at opposite axial end areas of the piston.
 32. Clutch system according to claim 31, characterized in that the piston surface (280; 580) associated with the pressure medium is smaller than the piston surface (262; 562) associated with the operating medium.
 33. Clutch system according to one of claims 30 to 32, characterized in that the secondary pump arrangement has a plurality of piston pumps which can be operated synchronously with offset piston stroke phases.
 34. Clutch system according to claim 33, characterized in that a first piston pump and a second piston pump can be operated synchronously with piston stroke phases that are offset by approximately 18°.
 35. Clutch system according to one of claims 30 to 32, characterized in that a suction stroke and a discharge stroke of the piston pump can be triggered alternately by means of a valve arrangement (218; 218 a) which is connected between the primary pump arrangement and the piston pump.
 36. Clutch system according to claim 35, characterized in that the suction stroke or the discharge stroke or both can be triggered by applying primary medium pressure to a control input (236; 536) of the piston pump associated with the respective stroke.
 37. Clutch system according to claim 36, characterized in that the piston pump has a return spring arrangement (244; 544) which acts on the piston (234; 534) and which is put under increasing tension during a suction stroke and discharge stroke.
 38. Clutch system according to one of claims 30 to 37, characterized in that at least one pressure reduction valve (246; 218) is provided, by means of which a primary medium pressure applied to a control input (236; 536) of the piston pump can be reduced by allowing the primary medium to flow off in order to trigger the suction stroke or discharge stroke of the piston pump.
 39. Clutch system according to claim 38, characterized in that the pressure reduction valve (246) is integrated in the secondary pump arrangement (230).
 40. Clutch system according to claim 39, characterized in that the pressure reduction valve (246) can be mechanically actuated through the intermediary of a stroke movement of a/the piston (234) of the piston pump and/or can be actuated through the intermediary of primary medium acting on the pressure reduction valve.
 41. Clutch system according to claim 40, characterized in that a plurality of valve elements (234, 242) of the pressure reduction valve (246) are displaceable between a first relative position identified as opening position and a second relative position identified as the closing position in response to the stroke movement of the piston (234) and/or in response to primary medium acting on at least one of the valve elements.
 42. Clutch system according to claim 41, characterized in that a first valve element (234) and a second valve element (242) are pretensioned in the direction of the open position by a pretensioning spring arrangement (254).
 43. Clutch system according to claim 41 or 42, characterized in that the piston (234) forms a valve element.
 44. Clutch system according to one of claims 40 to 43, characterized in that the pressure reduction valve (246) can be moved into an/the open position in that a valve element (234) executing the stroke movement along with the piston contacts a stop (270) and/or in that the pressure reduction valve is actuated by the piston contacting an actuating stop and can be brought into a/the closing position by primary medium acting on at least one valve element.
 45. Clutch system according to one of claims 20 to 44, characterized in that the secondary pump arrangement (220; 220 a) is constructed with at least one valve, particularly a non-return valve (252, 266; 582, 566), which prevents secondary medium from the secondary pump arrangement, possibly from the piston pump, from flowing back into the secondary medium reservoir and/or with at least one valve, particularly a non-return valve (252, 266; 582, 566), which prevents secondary medium from the side of the clutch arrangement from flowing back into the secondary pump arrangement, possibly into the piston pump.
 46. Clutch system according to one of claims 20 to 45, characterized in that the secondary pump arrangement (220) has at least one swirl conveying pump or centrifugal pump (300; 400) which can be driven by the primary medium supplied by the primary pump arrangement or at least one rotary positive-displacement pump, possibly a toothed gear pump (700; 800) or toothed ring pump, which can be driven by the primary medium supplied by the primary pump arrangement.
 47. Clutch system according to claim 46, characterized in that the swirl conveying pump or centrifugal pump or positive-displacement pump (700; 800) has at least one rotor (308; 408; 708 a; 708 b; 808 a, 808 b) with which the secondary medium interacts.
 48. Clutch system according to claim 47, characterized in that the rotor (308; 408; 708 a; 708 b; 808 a, 808 b) can be driven by means of a hydromotor (310; 410; 710; 810) receiving primary medium from the primary pump arrangement.
 49. Clutch system according to claim 48, characterized in that the hydromotor (310; 410; 710; 810) is constructed as a flow machine or positive-displacement machine.
 50. Clutch system according to claim 49, characterized in that the hydromotor is constructed as a rotary positive-displacement motor, possibly as a toothed gear motor (710; 810) or toothed ring motor.
 51. Clutch system according to claim 49 or 50, characterized in that the hydromotor has at least one rotor (310; 410; 710 a; 710 b; 810 a, 810 b) which interacts with the primary medium and which is coupled with respect to movement with the rotor (310; 410; 710 a; 710 b; 810 a, 810 b) interacting with the secondary medium.
 52. Clutch system according to one of claims 47 to 51, characterized in that the rotor (308; 408) interacting with the secondary medium and/or the rotor (310; 410) of the hydromotor comprise(s) a disk and/or a shaft with a flow geometry arrangement, possibly a blade arrangement.
 53. Clutch system according to one of claims 47 to 52, characterized in that the swirl conveying pump or centrifugal conveys the secondary medium in such a way that the secondary medium flows against the rotor (308; 408) in a substantially axial or radial-tangential direction, and that the operating medium flows off the rotor in a substantially axial or radial-tangential direction.
 54. Clutch system according to one of claims 51 to 53, characterized in that the hydromotor is constructed in such a way that the primary medium flows against the rotor (310; 410) in a substantially axial or radial-tangential direction and that the primary medium flows off the rotor in a substantially axial or radial-tangential direction.
 55. Clutch system according to claim 53 or 54, characterized in that a plurality of flow-in channels (314) and flow-off channels (316) which are arranged in a substantially rotational-symmetric manner with respect to the rotor are provided in a housing (306) accommodating the rotor (310) for essentially radial-tangential flow against the rotor in question and/or for essentially radial-tangential flow away from the respective rotor.
 56. Clutch system according to one of claims 52 to 55, characterized in that at least one rotor (410) interacting with the primary medium and at least one rotor (408) interacting with the secondary medium have rotational axes which are essentially coaxial to one another.
 57. Clutch system according to claim 56, characterized in that at least one operating medium flow (424) is guided substantially in axial direction at least in some areas as an annular flow surrounding at least a pressure medium flow (420) and/or surrounding the rotor (410) interacting with the pressure medium flow.
 58. Clutch system according to claim 57, characterized in that the pressure medium flow and the operating medium flow pass into a common medium flow.
 59. Clutch system according to one of claims 46 to 58, characterized in that the secondary pump arrangement has at least two rotors (708 a, 708 b; 808 a, 808 b) which interact with the secondary medium and which are not arranged coaxial to one another and/or in that the hydromotor has at least two rotors (710 a, 710 b; 810 a, 810 b) which interact with the primary medium and which are not arranged coaxial to one another.
 60. Clutch system according to claim 59, characterized in that a drive formation, possibly a toothing, of a first rotor (710 a; 810 a) of the hydromotor meshes with a driving formation, possibly a toothing, of a second rotor (710 b; 810 b) of the hydromotor.
 61. Clutch system according to claim 59 or 60, characterized in that a conveying formation, possibly a toothing, of a first rotor (708 a; 808 a) of the secondary pump arrangement meshes with a conveying formation, possibly a toothing, of a second rotor (708 b; 808 b) of the secondary pump arrangement.
 62. Clutch system according to one of claims 48 to 61, characterized in that at least one rotor (710 a, 710 b; 810 a) of the hydromotor interacting with the primary medium and at least one rotor (708 a, 708 b; 808 a) of the secondary pump arrangement interacting with the secondary medium are coupled with one another by means of at least one common shaft (725 a and 725 b; 825 a) which is shared by at least one rotor of the hydromotor and at least one motor of the secondary pump arrangement.
 63. Clutch system according to one of the preceding claims, characterized in that the clutch device (204, 206; 204 a, 206 a) is self-priming with respect to the operating medium, and in that the second pump arrangement (220; 208 a) allows operating medium which is sucked in by the clutch device to pass to the latter in a non-operational state.
 64. Clutch system according to one of claims 1 to 9, 20, 22 to 63, characterized in that the clutch arrangement (204, 206) can be actuated by means of the pump arrangement (208) or by means of pressure medium supplied by the first pump arrangement (208).
 65. Clutch system according to claim 64, characterized in that the pump arrangement (208) or the first pump arrangement (208) is designed to supply pressure medium at a pressure sufficient for actuating the clutch arrangement.
 66. Clutch system according to one of claims 10 to 19, 21 to 65, characterized in that the clutch device is provided for an operation under the influence of the operating medium supplied by the pump arrangement (208 a) or by the second pump arrangement (208 a).
 67. Clutch system according to one of the preceding claims, characterized in that the clutch arrangement is a wet clutch arrangement (204, 206; 204 a, 206 a), in that the operation is a wet operation under the influence of the operating medium, and in that the operating medium is an operating liquid, possibly a cooling liquid.
 68. Clutch system according to one of the preceding claims, characterized in that the clutch arrangement (204, 206; 204 a, 206 a) is a multi-disk clutch arrangement.
 69. Clutch system according to one of the preceding claims, characterized in that the pressure medium is a hydraulic pressure medium, particularly a hydraulic oil which may also serve as a cooling liquid.
 70. Clutch system according to one of the preceding claims, characterized in that the clutch device is a multiple clutch device (202; 202 a) with a plurality of clutch arrangements (204, 206; 204 a, 206 a).
 71. Clutch system according to one of the preceding claims, characterized in that operating medium can be supplied to the clutch arrangement through the intermediary of an operating medium storage which is connected or can be connected to the operating medium supply arrangement or to the pump arrangement or to the second pump arrangement.
 72. Clutch system according to one of the preceding claims, characterized in that the clutch arrangement can be actuated through the intermediary of a pressure medium storage which is connected or can be connected to the pump arrangement or to the pressure medium supply arrangement (220 a) or to the first pump arrangement (220 a). 